iOS Developer Tips Blog » Core Services

Remind Users to Restart Your App

John Muchow — Wed, 08 Feb 2012 08:03:02 +0000

This tip shows you how to create a local notification that will be trigged when a user exits your application. I would recommend you use this sparingly, for example, if the user was in the middle of setting up configuration information needed by an application.

Let’s start with a quick look at how this appears to the user. Assume the application TestApp is running in the foreground. When the application is put into the background by pressing the home button, within 1 second (see the code below), the following local notifications will appear (iOS 5 and iOS 4):

If the user taps on the message, the application return to the foreground.

The code is quite simple, it begins with creating an NSDate object with the current date/time, adding one second to that time, and setting the fire date for a local notification to the configured date. From there, setup the local notification messaging and wrap up by scheduling the notification with the OS.

- (void)applicationDidEnterBackground:(UIApplication *)application
{
  UILocalNotification *localNotification = [[[UILocalNotification alloc] init] autorelease];
 
  // Current date
  NSDate *date = [NSDate date]; 
 
  // Add one second to the current time
  NSDate *dateToFire = [date dateByAddingTimeInterval:1];
 
  // Set the fire date/time
  [localNotification setFireDate:dateToFire];
  [localNotification setTimeZone:[NSTimeZone defaultTimeZone]];    
 
  // Setup alert notification
  [localNotification setAlertBody:@"Tap to return to TestApp" ];
  [localNotification setAlertAction:@"Open TestApp"];
  [localNotification setHasAction:YES];
 
  [[UIApplication sharedApplication] scheduleLocalNotification:localNotification];
}

Once the notification has been presented to the user, and the user acknowledges, the method below in your application will be called once the app comes to the foreground:

- (void)application:(UIApplication *)application didReceiveLocalNotification:(UILocalNotification *)notification
{
  // Your code here...
}

Again, consider this option as a reminder to the user only in cases where an important process was underway, not as the default operation when the app goes into the background.

Get List of Installed International Keyboards

John Muchow — Tue, 27 Dec 2011 07:22:24 +0000

The NSUserDefaults object is typically used to save/restore your application related preferences, configuration data, etc – see Write and Read User Preferences for more information. In addition to application specifics, there is a system wide default list that is available to all applications, accessible using the class method standardUserDefaults in the NSUserDefaults object.

To get a list of the system wide settings:

NSDictionary* defaults = [[NSUserDefaults standardUserDefaults] dictionaryRepresentation];
NSLog(@"Defaults: %@", defaults);

A partial list of the output on my device follows:

Defaults: {
    AppleICUForce24HourTime = 0;
    AppleITunesStoreItemKinds =     (
        wemix,
        podcast,
        ...
    );
    AppleKeyboards =     (
        "en_US@hw=US;sw=QWERTY",
        "zh_Hant-HWR@sw=HWR",
        "emoji@sw=Emoji"
    );
    AppleKeyboardsExpanded = 1;
    AppleLanguages =     (
        en,
        "zh-Hant",
        fr,
        de,
  ...
}

As you can tell, the defaults returned above are contained within a dictionary object. The list of keyboards in the dictionary is stored as an NSArray object. To retrieve the array, simply request the object for the key “AppleKeyboards”

NSArray *array = [[NSUserDefaults standardUserDefaults] objectForKey:@"AppleKeyboards"];
NSLog(@"Keyboards: %@", array);

The output of all the installed international keyboards looks as follows:

Keyboards: (
    "en_US@hw=US;sw=QWERTY",
    "zh_Hant-HWR@sw=HWR",
    "emoji@sw=Emoji"
)

iOS 5 : Look Up Definitions Using Dictionary Service

John Muchow — Mon, 12 Dec 2011 08:09:22 +0000

With iOS 5, there is now a dictionary service that you can access to look up definitions of words. UIReferenceLibraryViewController makes it as easy as creating an instance of the class and providing a term/word to lookup. The view controller will handle the display of the definition and managing the UI (scrolling, etc).

// Create the view controller
UIReferenceLibraryViewController *reference = 
  [[[UIReferenceLibraryViewController alloc] initWithTerm:@"homebrew"] autorelease];
 
[self presentModalViewController:reference animated:YES];
}

If you provide a word that doesn’t exist in the reference, the view controller will look as shown in the screenshot on the right.

Rather than show a view controller with no definition, you can make a call to the class method dictionaryHasDefinitionForTerm prior to creating an object:

// Check if the term exists...
NSString *str = @"sabrage";
if ([UIReferenceLibraryViewController dictionaryHasDefinitionForTerm:str] == YES)
{
  // Create the view controller
  UIReferenceLibraryViewController *reference = 
    [[[UIReferenceLibraryViewController alloc] initWithTerm:str] autorelease];
 
  [self presentModalViewController:reference animated:YES];
}

The default animation is to slide the view controller up from the bottom. To change the animation, set setModalTransitionStyle:

NSString *str = @"homebrew";
if ([UIReferenceLibraryViewController dictionaryHasDefinitionForTerm:str] == YES)
{
  // Create the view controller
  UIReferenceLibraryViewController *reference = 
    [[[UIReferenceLibraryViewController alloc] initWithTerm:str] autorelease];
 
  // Change the transition style
  [reference setModalTransitionStyle:UIModalTransitionStyleFlipHorizontal];
 
  [self presentModalViewController:reference animated:YES];
}

Out of curiousity, I looked up a ridiculously long word, one that I would consider rather obscure: pneumonoultramicroscopicsilicovolcanoconiosis. Much to my surprise:

iOS 5 : Twitter Framework – Part 3 – Display List of Twitter Accounts

John Muchow — Mon, 14 Nov 2011 08:43:48 +0000

In the previous two iOS 5 Twitter Framework posts, I covered using TWTweetComposeViewController to display a pre-built controller for posting to Twitter and also wrote an example on how to use the TWRequest object to create an HTTP request to access the Twitter API.

Over the past few weeks I’ve had a number of requests to take this series one step further and show how to access the Twitter account data and display the information in a tableview. One of the common threads in the requests was how to do user interface updates as part of the completion handler code.

In this post I will create a short example to create and populate a tableview with the active Twitter account(s), calling code to update the UI from within the completion handler.

Setup the TableView

The interface for the primary view controller looks as follows:

@interface SandboxViewController : UIViewController 
{
  UIButton        *testButton;
  UITableView     *mainTableView;
  NSInteger       numberOfTwitterAccounts;
  ACAccountStore  *account;
  NSArray         *arrayOfAccounts;
}

The testButton will be used to initiate a request to get the Twitter account names, mainTableView will display those same names. numberOfTwitterAccounts will hold the count of valid Twitter accounts. account will contain Twitter account information and arrayOfAccounts stores an array of ACAccountStore objects.

The loadView method builds the basic UI for this example:

- (void)loadView 
{
  [self setView:[[[UIView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]] autorelease]];
	[[self view] setBackgroundColor:[UIColor blackColor]];
 
  // Create button  
  testButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
  [testButton setFrame:CGRectMake(20, 30, 280, 40)];
	[testButton setTitle:@"Get Twitter Accounts" forState:UIControlStateNormal];
  [testButton addTarget:self action:@selector(buttonPressed:) forControlEvents: UIControlEventTouchUpInside];        
  [[self view] addSubview:testButton];
 
  // Create table view
  mainTableView = [[UITableView alloc] initWithFrame:CGRectMake(0, 80, 320, 360) style: UITableViewStylePlain];
  [mainTableView setDelegate:self];
  [mainTableView setDataSource:self];
  [mainTableView setSeparatorStyle:UITableViewCellSeparatorStyleNone];
 
  // Start with an empty table
  numberOfTwitterAccounts = 0;
 
  [[self view] addSubview:mainTableView];
 
}

Notice I set numberOfTwitterAccounts to 0, so the table will be empty when the view controller is displayed – the code below shows how I use the numberOfTwitterAccounts variable when creating the tableview:

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
  // Set to number of twitter accounts
  return numberOfTwitterAccounts;
}

At this point, the user interface will look like this:

Get Twitter Account Data

When the button is pressed the following code will be called. The first step is to verify a Twitter account is available. From there, create an ACAccountStore object and an ACAccountType to get access to Twitter account data.

- (void)buttonPressed:(UIButton *)button
{
  // Is Twitter is accessible is there at least one account
  // setup on the device
  if ([TWTweetComposeViewController canSendTweet]) 
  {
    // Create account store, followed by a twitter account identifer
    account = [[ACAccountStore alloc] init];
    ACAccountType *accountType = [account accountTypeWithAccountTypeIdentifier:ACAccountTypeIdentifierTwitter];
 
    // Request access from the user to use their Twitter accounts.
    [account requestAccessToAccountsWithType:accountType withCompletionHandler:^(BOOL granted, NSError *error) 
    {
      // Did user allow us access?
      if (granted == YES)
      {
        // Populate array with all available Twitter accounts
        arrayOfAccounts = [account accountsWithAccountType:accountType];
        [arrayOfAccounts retain];
 
        // Populate the tableview
        if ([arrayOfAccounts count] > 0) 
          [self performSelectorOnMainThread:@selector(updateTableview) withObject:NULL waitUntilDone:NO];
      }
    }];
  }
}

Populate Tableview with Twitter Account Data

The last step is to add account names to the tableview. Notice in the code above, near the bottom inside the completion handler, the reference to performSelectorOnMainThread, this will invoke the method updateTableview on the main thread, which will allow the UI to be updated.

- (void)updateTableview
{
  // Update the row count used by tableview
  numberOfTwitterAccounts = [arrayOfAccounts count];
 
  // Reload the table with twitter account data
  [mainTableView reloadData];
}

With this code in place, once the table is reloaded, the method numberOfRowsInSection (shown above) will reflect the current number of rows for the table based on the number of active twitter accounts.

Here is the how each cell in the tableview is created:

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath 
{
  UITableViewCellStyle style =  UITableViewCellStyleDefault;
  UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"tableCell"];
 
  if (!cell) 
    cell = [[[UITableViewCell alloc] initWithStyle:style reuseIdentifier:@"tableCell"] autorelease];
 
  // View the array data 
  NSLog(@"Debug: %@", arrayOfAccounts);
 
  // Access the account data for each entry
  ACAccount *acct = [arrayOfAccounts objectAtIndex:indexPath.row];
 
  // Set the cell text to the username of the twitter account
  [[cell textLabel] setText:[acct username]];
 
  return cell;
}

Based on the indexpath (which row is being created), create an ACAccount object from the array of Twitter accounts and query the username variable to get the cell text.

With the two accounts active on my device, here is the output with the table populated:

Download the Twitter Framework Example

You can download the iOS 5 Twitter Framework Xcode project here.

iOS 5 : Twitter Framework – Part 2 – Call Twitter API with TWRequest

John Muchow — Mon, 24 Oct 2011 08:23:16 +0000

In the previous post on iOS 5 and the new Twitter framework, I walked through how to use TWTweetComposeViewController to display a pre-built controller for easily integrating and posting to Twitter.

In this post I will show you how to use the TWRequest object to create an HTTP request, and in turn, sending and processing the results of the request. There are three primary components of a Twitter request: the URL of the desired Twitter service you are after, the type of HTTP request (GET, POST or DELETE) and any query parameters (required or optional) of the service requested. It’s also worth noting, using when using TWRequest user authentication is handled for you.

Twitter Search

By looking at the Twitter API I found how to properly setup a search request. Below I do a search for the string “iOS 5″, which looks like this when url-encoded: “q=iOS%205″. Check out the API for more information about the additional parameters.

#import 
 
...
 
// Do a simple search, using the Twitter API
TWRequest *request = [[TWRequest alloc] initWithURL:[NSURL URLWithString:
   @"http://search.twitter.com/search.json?q=iOS%205&rpp=5&with_twitter_user_id=true&result_type=recent"] 
   parameters:nil requestMethod:TWRequestMethodGET];
 
// Notice this is a block, it is the handler to process the response
[request performRequestWithHandler:^(NSData *responseData, NSHTTPURLResponse *urlResponse, NSError *error)
{
  if ([urlResponse statusCode] == 200) 
  {
    // The response from Twitter is in JSON format
    // Move the response into a dictionary and print
    NSError *error;        
    NSDictionary *dict = [NSJSONSerialization JSONObjectWithData:responseData options:0 error:&error];
    NSLog(@"Twitter response: %@", dict);                           
  }
  else
    NSLog(@"Twitter error, HTTP response: %i", [urlResponse statusCode]);
}];

And here is what a partial response, in JSON, looks like:

Twitter response: {
    "completed_in" = "0.179";
    "max_id" = 128283809723592705;
    "max_id_str" = 128283809723592705;
    "next_page" = "?page=2&max_id=128283809723592705&q=ios%205&rpp=5&with_twitter_user_id=1";
    page = 1;
    query = "ios+5";
    "refresh_url" = "?since_id=128283809723592705&q=ios%205&with_twitter_user_id=1";
    results =     (
                {
            "created_at" = "Mon, 24 Oct 2011 01:36:58 +0000";
            "from_user" = XXXXXXXXXXX;
            "from_user_id" = 14379847;
            "from_user_id_str" = 14379847;
            geo = "";
            id = 128283809723592705;
            "id_str" = 128283809723592705;
            "iso_language_code" = en;
            metadata =             {
                "result_type" = recent;
            };
  ...
}

You can use the above query even if there is no Twitter account setup on the device – for example, copy/paste the URL http://search.twitter.com/search.json?q=iOS%205&rpp=5&with_twitter_user_id=true&result_type=recent into a browser to view the search request.

Twitter Post

Let’s look at how to create a custom tweet, that is, post to Twitter without using TWTweetComposeViewController.

#import 
#import 
 
...
 
if ([TWTweetComposeViewController canSendTweet]) 
{
  // Create account store, followed by a twitter account identifier
  // At this point, twitter is the only account type available
  ACAccountStore *account = [[ACAccountStore alloc] init];
  ACAccountType *accountType = [account accountTypeWithAccountTypeIdentifier:ACAccountTypeIdentifierTwitter];
 
  // Request access from the user to access their Twitter account
  [account requestAccessToAccountsWithType:accountType withCompletionHandler:^(BOOL granted, NSError *error) 
  {
    // Did user allow us access?
    if (granted == YES)
    {
      // Populate array with all available Twitter accounts
      NSArray *arrayOfAccounts = [account accountsWithAccountType:accountType];
 
      // Sanity check
      if ([arrayOfAccounts count] > 0) 
      {
        // Keep it simple, use the first account available
        ACAccount *acct = [arrayOfAccounts objectAtIndex:0];
 
        // Build a twitter request
        TWRequest *postRequest = [[TWRequest alloc] initWithURL:
                                  [NSURL URLWithString:@"http://api.twitter.com/1/statuses/update.json"] 
                                  parameters:[NSDictionary dictionaryWithObject:@"Custom tweet from iOS 5 Twitter framework. Visit iOSDeveloperTips.com for more information." 
                                  forKey:@"status"] requestMethod:TWRequestMethodPOST];
 
        // Post the request
        [postRequest setAccount:acct];
 
        // Block handler to manage the response
        [postRequest performRequestWithHandler:^(NSData *responseData, NSHTTPURLResponse *urlResponse, NSError *error) 
        {
          NSLog(@"Twitter response, HTTP response: %i", [urlResponse statusCode]);
        }];
      }
    }
  }];
}

On line 14, the request for access will show a dialog as follows:

If all is well, we create an array of the available accounts, and using the first entry, create a TWRequest to post a tweet. Check out the Twitter API for specifics on the parameters.

Once the tweet has been posted, there is block handler to print the response to the console. A successful tweet should print: Twitter response, HTTP response: 200.

The successful Twitter post looks will look like this:

One last note, don’t forget to add the Twitter and Accounts frameworks to your project before compiling.

iOS 5 : Twitter Framework – Part 1 – Compose a Tweet with TWTweetComposeViewController

John Muchow — Mon, 17 Oct 2011 08:21:04 +0000

This is the first post of two on how to work with the new Twitter framework in an iOS 5 app. This post will cover the basics to create and display a dialog for composing a tweet. Part 2 in this series can be found here.

The primary controller for working with Twitter in iOS 5 is TWTweetComposeViewController. This object handles all the UI related work to display and manage input – you can pre-populate the initial text, add an image as well as a URL. The code is straight forward to get things rolling:

#import 
 
...
 
// Create the view controller
TWTweetComposeViewController *twitter = [[TWTweetComposeViewController alloc] init];
 
// Optional: set an image, url and initial text
[twitter addImage:[UIImage imageNamed:@"iOSDevTips.png"]];
[twitter addURL:[NSURL URLWithString:[NSString stringWithString:@"http://iOSDeveloperTips.com/"]]];
[twitter setInitialText:@"Tweet from iOS 5 app using the Twitter framework."];
 
// Show the controller
[self presentModalViewController:twitter animated:YES];
 
// Called when the tweet dialog has been closed
twitter.completionHandler = ^(TWTweetComposeViewControllerResult result) 
{
  NSString *title = @"Tweet Status";
  NSString *msg; 
 
  if (result == TWTweetComposeViewControllerResultCancelled)
    msg = @"Tweet compostion was canceled.";
  else if (result == TWTweetComposeViewControllerResultDone)
    msg = @"Tweet composition completed.";
 
  // Show alert to see how things went...
  UIAlertView* alertView = [[UIAlertView alloc] initWithTitle:title message:msg delegate:self cancelButtonTitle:@"Okay" otherButtonTitles:nil];
  [alertView show];
 
  // Dismiss the controller
  [self dismissModalViewControllerAnimated:YES];
};

Notice the Objective-C block (more on blocks here) that is defined for the completion handler, this is called once the user has finished composing the tweet.

Before running the code you’ll need to configure a Twitter account. If you skip this step you’ll see the dialog on the left below. The image on the right is the settings screen to configure an account. Also, you will need to add the Twitter framework to your Xcode project before compiling.

The screenshot below shows the Twitter view controller poplated with the content shown above.

Below is a screenshot from the twitter page showing how the tweet above looks at twitter.com/iOSDevTips.

That’s all you need to get started for basic twitter integration. In the next post I’ll go into more detail including a look at the ACAccountStore for managing accounts and TWRequest for sending HTTP requests to Twitter.

How to Keep the Screen from Locking

John Muchow — Mon, 25 Jul 2011 08:31:01 +0000

By default, iOS will lock the screen and disable the touch sensor if there are no touch events for a specified period of time. Depending on your application, there may be times that you need to keep the screen from locking. For example, if your application is primarily accelerometer driven (such as a game), there may be minimal touch events to keep the screen from reseting its internal timer.

You can disable the idle timer through the idleTimerDisabled property of the shared UIApplication object:

// Disable the idle timer
[[UIApplication sharedApplication] setIdleTimerDisabled: YES];
 
// Or for those who prefer dot syntax:
[UIApplication sharedApplication].idleTimerDisabled = YES;

Using Keychain to Store Username and Password

John Muchow — Mon, 11 Jul 2011 08:09:52 +0000

The keychain services on iOS provide a means to securely store content such as passwords, keys, certificates, etc. Each iOS application has a separate set of keychain items. Beginning with iOS 3.0, it is possible to share keychain items across applications.

In this tip, I will demonstrate a starting point for working with the keychain by storing and retrieving a username and password.

Keychain Demo Application

Before going any further, let me show you the sample application I wrote to test keychain access. The screenshot on the left shows two fields, one each for username and passord, along with a button to initiate the process for writing to the keychain. The figure on the right shows the fields populated upon application startup by retrieving the username and password from the keychain.

Below are the definitions for the textfields and the button:

UITextField *username = [[UITextField alloc] initWithFrame:CGRectMake(40, 30, 240, 30)];
[username setBorderStyle:UITextBorderStyleRoundedRect];
...
 
UITextField *password = [[UITextField alloc] initWithFrame:CGRectMake(40, 75, 240, 30)];
[password setBorderStyle:UITextBorderStyleRoundedRect];
...
 
UIButton *testButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
[testButton setFrame:CGRectMake(80, 130, 160, 40)];
[testButton addTarget:self action:@selector(buttonPressed:) forControlEvents: UIControlEventTouchUpInside];        
...

Keychain Wrapper

Apple has written an Objective-C wrapper that you can use to simplify working with the keychain, the files in the wrapper are KeychainItemWrapper.h and KeychainItemWrapper.m, both are included in the attached Xcode project.

To use the wrapper, allocate a new KeychainItemWrapper object as shown below:

KeychainItemWrapper *keychain = 
 [[KeychainItemWrapper alloc] initWithIdentifier:@"TestAppLoginData" accessGroup:nil];

I’ve specified a unique identifier (“TestAppLoginData”) for the username and password pair that I want to store in the keychain. The accessGroup is set to nil as only one application will access the keychain items in this application.

Writing to the Keychain

Once the button is pressed to save the username and password, writing to the keychain is quite straight-forward. For the username, I set an object (the username text) with the key kSecAttrAccount. I follow this by setting another object, this time the password text, with the key kSecValueData.

- (void)buttonPressed:(UIButton *)button
{
  if (button == testButton)
  {	
    // Store username to keychain 	
    if ([username text])
      [keychain setObject:[username text] forKey:(id)kSecAttrAccount];
 
    // Store password to keychain
    if ([password text])
      [keychain setObject:[password text] forKey:(id)kSecValueData];    	    
  }
}

Reading from the Keychain

To populate the textfields with stored keychain items at application startup, once the textfields are defined, I read the two key-value pairs:

// Get username from keychain (if it exists)
[username setText:[keychain objectForKey:(id)kSecAttrAccount]];
NSLog(@"username: %@", [username text]);

For the password, I request the key kSecValueData:

// Get password from keychain (if it exists)  
[password setText:[keychain objectForKey:(id)kSecValueData]];
NSLog(@"password: %@", [password text]);

For this simple application, at this point we are done, that’s all that is required to write and read items with the keychain.

Notes:

Writing and retrieving values from the keychain doesn’t seem to work in the simulator.
Uninstalling an application will not remove the items from the keychain. If you run the demo application on your device, and uninstall the app, the username and password will remain in the keychain (a firmware reset will, of course, remove the keychain values).

Apple Keychain Resources

Keychain Services Programming Guide

GenericKeychain Example (source code)

Keychain Xcode Project

Download the demo project: – Store Username and Password to Keychain

How to Send an SMS Progammatically

John Muchow — Wed, 01 Jun 2011 11:08:45 +0000

This post shows the basics for sending an SMS message from within an iPhone application. The class you’ll need to use is MFMessageComposeViewController which presents the standard SMS interface for composing and sending messages. As you’ll see in the example that follows, you can also pre-populate the body of the message as well one or more recipients for the SMS.

SMS View Controller Interface

The view controller that will send the SMS is shown below, notice the message composer import statement as well as the reference to the protocol MFMessageComposeViewControllerDelegate. The delegate has just one method where you can check the result of the message (sent, cancelled or failed) and this is also where you dismiss the view controller show the message composer – more on this method in a moment.

#import 
#import 
 
@interface TestViewController : UIViewController 
{
  UIButton *buttonSMS;
}
 
@end

SMS View Controller Implementation

The implementation code begins with a very simple loadView method, this is where the view is created and a button defined to initiate sending the SMS:

- (void)loadView 
{
  [self setView:[[[UIView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]] autorelease]];  
 
  buttonSMS = [UIButton buttonWithType:UIButtonTypeRoundedRect];
  [buttonSMS setFrame:CGRectMake(0, 0, 180, 40)];
  [buttonSMS setCenter:CGPointMake(160, 208)];
  [buttonSMS setTitle:@"Send SMS" forState:UIControlStateNormal];
  [buttonSMS addTarget:self action:@selector(buttonPressed:) forControlEvents:UIControlEventTouchUpInside];
  [[self view] addSubview:buttonSMS];
}

Notice in the button code above the target and action values, when a touch up inside event occurs, the method buttonPressed is called. Inside this method we call a method to send an SMS, passing in the body of the SMS message as well as the phone numbers of the recipients of the message:

- (void)buttonPressed:(UIButton *)button
{
  if (button == buttonSMS)
    [self sendSMS:@"Body of SMS..." recipientList:[NSArray arrayWithObjects:@"+1-111-222-3333", @"111-333-4444", nil]];
}

Sending an SMS

The last two methods to cover manage creating an instance of MFMessageComposeViewController to create the SMS content and another method for handling the user interaction with the SMS dialog.

- (void)sendSMS:(NSString *)bodyOfMessage recipientList:(NSArray *)recipients
{
  MFMessageComposeViewController *controller = [[[MFMessageComposeViewController alloc] init] autorelease];
  if([MFMessageComposeViewController canSendText])
  {
    controller.body = bodyOfMessage;    
    controller.recipients = recipients;
    controller.messageComposeDelegate = self;
    [self presentModalViewController:controller animated:YES];
  }    
}
 
- (void)messageComposeViewController:(MFMessageComposeViewController *)controller didFinishWithResult:(MessageComposeResult)result
{
  [self dismissModalViewControllerAnimated:YES];
 
  if (result == MessageComposeResultCancelled)
    NSLog(@"Message cancelled")
  else if (result == MessageComposeResultSent)
    NSLog(@"Message sent")  
  else 
    NSLog(@"Message failed")  
}

In the sendSMS method, the first check is to ensure the device supports sending messages. Upon success, the body, recipients and delegate are set. The last step is to present a modal view controller to show the SMS dialog.

Once the user taps either the cancel or send on the SMS dialog, the method messageComposeViewController is called, here you can check whether the message was sent, cancelled or failed. This is also the time to dismiss the view controller presented in the previous method.

Build the Project

One last step before you can compile the application, you’ll need to add the MessageUI.framework to your project.

SMS on Simulator

You cannot send SMS messages from within the simulator, if you do, you will see the message shown below:

Send SMS Xcode Project

Download the send SMS Xcode project.

Local Notifications

John Muchow — Mon, 16 May 2011 09:04:47 +0000

In this post I’ll show you the basics for working with local notifications, which are notifications generated from the device itself, versus a remote notification (aka push notification) that is sent from a remote server. Local notifications are useful when you need to schedule a reminder or otherwise notify the user of a future event.

Creating and Processing Local Notifications

Local notifications are scheduled for a future date by creating a UILocalNotification object. When creating the notification you can also specify the type of notification(s) to send, a badge, alert or sound.

If a local notification arrives on the application that is not running in the foreground, the notification is delivered (that is, the alert shown, the badge set, sound played). If the notification is an alert, a dialog is shown to the user, along with an option to open the application. If the user chooses to open the app, the method didFinishLaunchingWithOptions in the application delegate is called passing in the local notification object.

If the application is running when a local notification is received, the method didReceiveLocalNotification is called, again, passing in the local notification object.

Screenshots

The app I’ve written to work with notification has a range of buttons to schedule various types of notifications:

Once you choose an option, the notification is scheduled – to keep things simple, in my application I’ve set all notifications to arrive in 60 seconds. The screenshot below shows an incoming notification when the app has been put into the background.

The screenshot below is an alert I display from within the method called when a notification arrives.

Methods in the App Delegate

The application delegate contains the two methods needed for managing incoming notifications. The method didFinishLaunchingWithOptions is shown below. Notice the check of the launchOptions parameter early in the method, if this value is nil, this is a standard application startup. If the value is not nil, the application was started based on a notification presented to the user – in this case I show an alert along with a few debug messages, including the payload data received from the notification (more on this below).

The code in the later half of the method is typical startup stuff, creating a window and view controller, etc

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
  // Handle launching from a notification
  UILocalNotification *notification = [launchOptions objectForKey:UIApplicationLaunchOptionsLocalNotificationKey];
 
  // If not nil, the application was based on an incoming notifiation
  if (notification) 
  {
    NSLog(@"Notification initiated app startup");
 
    // Access the payload content
    NSLog(@"Notification payload: %@", [notification.userInfo objectForKey:@"payload"]);
 
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Launched with Options" 
                              message:@"Notification initiated app startup" 
                              delegate:self cancelButtonTitle:@"Ok" 
                              otherButtonTitles:nil];
    [alert show];
    [alert release];
  }
 
  // Reset the badge
  [application setApplicationIconBadgeNumber:0];
 
  // Create and initialize the window
  window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
 
  // Create test view controller
  vc = [[TestViewController alloc] init];
 
  [window addSubview:vc.view];
  [window makeKeyAndVisible];
 
  return YES;
}

The second method in the application delegate is didReceiveLocalNotification which will be called when a notification arrives while the applications is running. In this method I show an alert and also write the notification payload to the debug console. For the payload, I am creating an array of objects, packaging the array within a dictionary and passing the later along with the notification.

- (void)application:(UIApplication *)application didReceiveLocalNotification:(UILocalNotification *)notification 
{
  UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Launched with Options" 
                            message:@"Incoming notification in running app" 
                            delegate:self cancelButtonTitle:@"Ok" 
                            otherButtonTitles:nil];
  [alert show];
  [alert release];
 
  NSLog(@"Incoming notification in running app");
 
  // Access the payload content
  NSLog(@"Notification payload: %@", [notification.userInfo objectForKey:@"payload"]);
}

Scheduling a Local Notification

The buttons shown in the screenshot above are how we initiate creating and scheduling a local notification. Before handling each event there is some common code for creating a UILocalNotification object, setting the fire date and populating the data (payload) that will accompany the notification.

- (void)buttonPressed:(UIButton *)button
{
  UILocalNotification *localNotification = [[[UILocalNotification alloc] init] autorelease];
 
  if (!localNotification) 
    return;
 
  // Current date
  NSDate *date = [NSDate date]; 
 
  // Add one minute to the current time
  NSDate *dateToFire = [date dateByAddingTimeInterval:60];
 
  // Set the fire date/time
  [localNotification setFireDate:dateToFire];
  [localNotification setTimeZone:[NSTimeZone defaultTimeZone]];
 
  // Create a payload to go along with the notification
  NSArray *array = [NSArray arrayWithObjects:@"Value 1", @"Value 2", nil];
  NSDictionary *data = [NSDictionary dictionaryWithObject:array forKey:@"payload"];
  [localNotification setUserInfo:data];
 
  if (button == buttonAlert || button == buttonAll)
  {	
    // Setup alert notification
    [localNotification setAlertBody:@"Incoming Local Notification" ];
    [localNotification setAlertAction:@"Open App"];
    [localNotification setHasAction:YES];      
  }
 
  if (button == buttonBadge || button == buttonAll)
  {
    // Set badge notification, increment current badge value
    [localNotification setApplicationIconBadgeNumber:[[UIApplication sharedApplication] applicationIconBadgeNumber] + 1];
  }
 
  if (button == buttonSound || button == buttonAll)
  {
    // Setup sound notification
    [localNotification setSoundName:UILocalNotificationDefaultSoundName];			  
  }
 
  // Schedule the notification        
  [[UIApplication sharedApplication] scheduleLocalNotification:localNotification];
}

Local Notification Xcode Project

Download Xcode Local Notification Example