iPhone-Simulator Cropper

This tool works by capturing the screen of the simulator runnning on your system. One really slick feature is the option to create captured images in two primary formats – first, a format suitable for upload to iTunes for your application screenshots – second, capturing a screenshot that is suitable for display on a website.

The following images show the iPhone-Simulator Cropper application, as well as two sample images captured:

iTunes Connect / App Store:

Website (iPhone Device from Apple Marketing):

However, they are times when having a method to truncate a string without using a UI control would be handy. In this post I’ll create a category which will add a method to the NSString class to do just that. You can read more about working with categories in this post: Introduction to Categories.

NSString Category

Start by creating a new interface file with the name: NSString+TruncateToWidth.h – appending the method name to the class is a common naming convention when working with categories.

The code below defines a method that will be available to all NSString objects. The method will truncate a string to a specific width, using the font size to properly determine the string size before truncating:

@interface NSString (TruncateToWidth)
 
- (NSString*)stringByTruncatingToWidth:(CGFloat)width withFont:(UIFont *)font;
 
@end

Code to Truncate NSString

The implementation of the stringByTruncatingToWidth method follows, add this code to the NSString+TruncateToWidth.m file.

#import "NSString+TruncateToWidth.h"
 
#define ellipsis @"…"
 
@implementation NSString (TruncateToWidth)
 
- (NSString*)stringByTruncatingToWidth:(CGFloat)width withFont:(UIFont *)font
{
  // Create copy that will be the returned result
  NSMutableString *truncatedString = [[self mutableCopy] autorelease];
 
  // Make sure string is longer than requested width
  if ([self sizeWithFont:font].width > width)
  {
    // Accommodate for ellipsis we'll tack on the end
    width -= [ellipsis sizeWithFont:font].width;
 
    // Get range for last character in string
    NSRange range = {truncatedString.length - 1, 1};
 
    // Loop, deleting characters until string fits within width
    while ([truncatedString sizeWithFont:font].width > width) 
    {
      // Delete character at end
      [truncatedString deleteCharactersInRange:range];
 
      // Move back another character
      range.location--;
    }
 
    // Append ellipsis
    [truncatedString replaceCharactersInRange:range withString:ellipsis];
  }
 
  return truncatedString;
}
 
@end

Notice that the desired final width of the string is passed in, as well as the font that will be used when calculating the size (width) of the string. The process is quite simple: change the incoming width to accommodate an ellipsis on the end of the string – loop through the string removing characters from the end until the desired width is reached – append an ellipsis onto the string.

Calling the Truncate NSString Method

You can now call the method stringByTruncatingToWidth:withFont: on any NSString object:

NSString *str = @"Lorem ipsum dolor sit amet, consectetuer adipiscing";
 
// Adjust the width parameter to change the final string width
str = [str stringByTruncatingToWidth:170 withFont:[UIFont systemFontOfSize:15]];
NSLog(@"%@", str);

The output from above would look as follows:

Lorem ipsum dolor sit…

You can download older versions of Xcode by logging into Apple Developer Connection – Downloads and ADC Program Assests (http://connect.apple.com) – You will need to be a member of the developer program to login.

Once on the site, from the Downloads section, choose Developer Tools – you will be shown with a list of all Xcode versions, back to 1.0 released in October of 2004.

For both posts, in order to create a working example that one could download and run as is, the code examples referenced a movie that I included in the application bundle. Although handy, this prompted a number of questions about how to play a movie from a remote resource.

I’ve updated the original examples for both posts, with an option to play movies from the application bundle or from a remote server.

Play Movie from Server

The first change I made was in CustomMoviePlayerViewController.m, where I added a method to initialize the movie player with a NSURL object:

- (id)initWithURL:(NSURL *)URL
{
  if (self = [super init])
  {
    movieURL = URL;
    [movieURL retain];
 
  }
  return self;
}
 
- (id)initWithPath:(NSString *)moviePath
{
  if (self = [super init])
  {
    movieURL = [NSURL fileURLWithPath:moviePath];    
    [movieURL retain];
  }
  return self;
}

For both methods, the end result is an initialized NSURL object.

The other code change is in TestViewController.m where I updated the loadMoviePlayer method to support calling either of the above methods:

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- (void)loadMoviePlayer
{  
/*
  // Play movie from app bundle
  NSString *path = [[NSBundle mainBundle] pathForResource:@"Movie-1" ofType:@"mp4" inDirectory:nil];
  moviePlayer = [[[CustomMoviePlayerViewController alloc] initWithPath:path] autorelease];
*/
 
  // Play movie from URL
  NSURL *movieURL = [NSURL URLWithString:@"http://someurlsomewhere.com/movie.mp4"];
  moviePlayer = [[[CustomMoviePlayerViewController alloc] initWithURL:movieURL] autorelease];
 
  // Show the movie player as modal
  [self presentModalViewController:moviePlayer animated:YES];
 
  // Prep and play the movie
  [moviePlayer readyPlayer];    
}

Comment in/out the relevant code in lines 4 – 11 to swap between playing from a file in the bundle and a movie accessible on a remote server.

Download Movie Player Source Code

MoviePlayer in Landscape Mode

MoviePlayer in Portrait Mode (requires 3.2 OS and greater)

In this post I want to show you a few minor changes you can make to the previous app to display a movie in portrait mode, something that was not possible in earlier (pre 3.2) OS versions. With that said, back in January of 2010 I did cover a means to create the illusion that a movie was in portrait mode, if this piques your interest, have a look here: Play iPhone Movies in Portrait Mode with MPMoviePlayerController using Public API’s

The figure below shows the same movie as played back in landscape and portrait:

Play Movies in Portrait Mode

The code below is from the previous post and shows how to configure the movie player view to display in landscape:

MPMoviePlayerController *mp =  [[MPMoviePlayerController alloc]
     initWithContentURL:movieURL];
 
...
 
- (void) moviePlayerLoadStateChanged:(NSNotification*)notification 
{
  ...
  // Rotate the view for landscape playback
  [[self view] setBounds:CGRectMake(0, 0, 480, 320)];
  [[self view] setCenter:CGPointMake(160, 240)];
  [[self view] setTransform:CGAffineTransformMakeRotation(M_PI / 2)]; 
 
  // Set frame of movieplayer
  [[mp view] setFrame:CGRectMake(0, 0, 480, 320)];
 
  ...
}

To playback a movie in portrait mode is as easy as removing the code for the rotation and changing the frame of the movieplayer. I’ve also added a call to scale the movie so it fills the screen, this will maintain the aspect ratio.

- (void) moviePlayerLoadStateChanged:(NSNotification*)notification 
{
  ...
  // Rotate the view for landscape playback
  //	  [[self view] setBounds:CGRectMake(0, 0, 480, 320)];
  //		[[self view] setCenter:CGPointMake(160, 240)];
  //		[[self view] setTransform:CGAffineTransformMakeRotation(M_PI / 2)]; 
 
  // Set frame of movieplayer
  // [[mp view] setFrame:CGRectMake(0, 0, 480, 320)];
  [[mp view] setFrame:CGRectMake(0, 160, 320, 160)];
 
  // Scale uniformly, maintaining aspect ratio
  [mp setScalingMode:MPMovieScalingModeAspectFill];
 
  ...
}

This approach works on 3.2 (iPad) as well as 4.0 and greater. Needless to say, given the large display on the iPad this is a nice alternative as the user can watch videos without rotating the device.

Source Code

Download the source code to build an iPhone app that displays movies in portrait mode.

In the next post, Display iPhone Movies in Portrait Mode, I’ll show how to create a movie player that runs in a view that is not fullscreen as well as how to show a few lines of code to display a movie in portrait mode – the one caveat here is that both of the tips in the second post will apply only to OS versions 3.2 and up.

What’s Changed with MPMoviePlayerController in 3.2 and 4.0?

There are any number of changes in the MPMoviePlayerController, however, a few standout as potential roadblocks to getting a movie to display:

- In 3.1 and earlier versions, MPMoviePlayerController was full-screen only. Playing a movie was straight-forward, create a player, initialize with a file (path or URL) and call a method to start playback – the rest was taken care of for you.

- With 3.2 and later, movies can playback in fullscreen or a custom view, as well as portrait or landscape.

- The notification MPMoviePlayerContentPreloadDidFinishNotification has been deprecated. This notification was used in earlier versions to notify observers that a movie was loaded and ready to play.

The Movie Application

The application in this post is quite simple, it consists of a view controller with nothing more than a button to start playback and a second view controller to manage a MPMoviePlayerController and the NSURL of the movie. The two views are shown in the figures below:

Primary View Controller

The interface definition for the primary view is shown below:

#import <UIKit/UIKit.h>
 
@class CustomMoviePlayerViewController;
 
@interface TestViewController : UIViewController
{
  CustomMoviePlayerViewController  *moviePlayer;
  UIButton  *playButton;
}
 
@end

CustomMoviePlayerViewController is the controller for managing the movie, we’ll look at that code in a moment.

In the code below we create the view, add a play button, create a method for processing a button press event and within loadMoviePlayer, we get a reference to the movie file and create an instance of the CustomMoviePlayerViewController, which will load and play the movie.

- (void)loadView
{
  // Setup the view
  [self setView:[[[UIView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]] autorelease]];
  [[self view] setBackgroundColor:[UIColor grayColor]];
  [[self view] setUserInteractionEnabled:YES];
 
  // Add play button 
  playButton = [[UIButton alloc] initWithFrame:CGRectMake(53, 212, 214, 36)];    
  [playButton setBackgroundImage:[UIImage imageNamed:@"playButton.png"] forState:UIControlStateNormal];
  [playButton addTarget:self action:@selector(buttonPressed:) forControlEvents: UIControlEventTouchUpInside];    
  [[self view] addSubview:playButton];  
}
 
- (void)buttonPressed:(UIButton *)button
{
  // If pressed, play movie
  if (button == playButton)
    [self loadMoviePlayer];	
}
 
- (void)loadMoviePlayer
{  
  // Play movie from the bundle
  NSString *path = [[NSBundle mainBundle] pathForResource:@"Movie-1" ofType:@"mp4" inDirectory:nil];
 
  // Create custom movie player   
  moviePlayer = [[[CustomMoviePlayerViewController alloc] initWithPath:path] autorelease];
 
  // Show the movie player as modal
  [self presentModalViewController:moviePlayer animated:YES];
 
  // Prep and play the movie
  [moviePlayer readyPlayer];    
}

Notice that the movie for this example is loaded from the application bundle. Also, once the custom movie player is created, the view is shown as a modal view.

Custom Movie Player View Controller

The interface definition for the movie view controller is below:

@interface CustomMoviePlayerViewController : UIViewController 
{
  MPMoviePlayerController *mp;
  NSURL  *movieURL;
}
 
- (id)initWithPath:(NSString *)moviePath;
- (void)readyPlayer;
 
@end

The initialization code is where the movie player and associated URL are created. The primary goal of the initialization is to create the NSURL needed by the movie player.

- (id)initWithPath:(NSString *)moviePath
{
  // Initialize and create movie URL
  if (self = [super init])
  {
    movieURL = [NSURL fileURLWithPath:moviePath];    
    [movieURL retain];
  }
  return self;
}

The code to create the player and setup the notifications is where we start to deal with the differences in how the movie player works on various OS versions. Notice below the call to respondsToSelector, this is the Apple recommended way to check for feature availability, versus looking for a specific OS version.

For devices running 3.2 and above, the movie player controller has a method named loadstate, if this exists we can access a few additional methods to set the player to fullscreen as well as request the movie to begin preloading.

Equally important is the distinction of which notification to setup – see lines 16 and 24.

You can read more about managing different OS version in this post Developing iPhone Apps with iOS4 SDK, Deploying to 3.x Devices

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- (void) readyPlayer
{
   mp =  [[MPMoviePlayerController alloc] initWithContentURL:movieURL];
 
  // For 3.2 devices and above
  if ([mp respondsToSelector:@selector(loadState)]) 
  {
    // Set movie player layout
    [mp setControlStyle:MPMovieControlStyleFullscreen];
    [mp setFullscreen:YES];
 
    // May help to reduce latency
    [mp prepareToPlay];
 
    // Register that the load state changed (movie is ready)
    [[NSNotificationCenter defaultCenter] addObserver:self 
        selector:@selector(moviePlayerLoadStateChanged:) 
        name:MPMoviePlayerLoadStateDidChangeNotification 
        object:nil];
  }  
  else
  {
    // Register to receive a notification when the movie is in memory and ready to play.
    [[NSNotificationCenter defaultCenter] addObserver:self 
        selector:@selector(moviePreloadDidFinish:) 
        name:MPMoviePlayerContentPreloadDidFinishNotification 
        object:nil];
  }
 
  // Register to receive a notification when the movie has finished playing. 
  [[NSNotificationCenter defaultCenter] addObserver:self 
        selector:@selector(moviePlayBackDidFinish:) 
        name:MPMoviePlayerPlaybackDidFinishNotification 
        object:nil];
}

The next two chunks of code are for each of the selectors, one for each notification. The code below is for earlier OS versions – nothing more than removing the notification and asking the movie to play.

/*---------------------------------------------------------------------------
* For 3.1.x devices
* For 3.2 and 4.x see moviePlayerLoadStateChanged: 
*--------------------------------------------------------------------------*/
- (void) moviePreloadDidFinish:(NSNotification*)notification 
{
  // Remove observer
  [[NSNotificationCenter 	defaultCenter] 
    removeObserver:self
    name:MPMoviePlayerContentPreloadDidFinishNotification
    object:nil];
 
  // Play the movie
   [mp play];
}

For the notification generated in 3.2 and above, there are a few more details to tend to:

/*---------------------------------------------------------------------------
* For 3.2 and 4.x devices
* For 3.1.x devices see moviePreloadDidFinish:
*--------------------------------------------------------------------------*/
- (void) moviePlayerLoadStateChanged:(NSNotification*)notification 
{
  // Unless state is unknown, start playback
  if ([mp loadState] != MPMovieLoadStateUnknown)
  {
    // Remove observer
    [[NSNotificationCenter defaultCenter] 
      removeObserver:self
      name:MPMoviePlayerLoadStateDidChangeNotification 
      object:nil];
 
    // When tapping movie, status bar will appear, it shows up
    // in portrait mode by default. Set orientation to landscape
    [[UIApplication sharedApplication] setStatusBarOrientation:UIInterfaceOrientationLandscapeRight animated:NO];
 
    // Rotate the view for landscape playback
    [[self view] setBounds:CGRectMake(0, 0, 480, 320)];
    [[self view] setCenter:CGPointMake(160, 240)];
    [[self view] setTransform:CGAffineTransformMakeRotation(M_PI / 2)]; 
 
    // Set frame of movie player
    [[mp view] setFrame:CGRectMake(0, 0, 480, 320)];
 
    // Add movie player as subview
    [[self view] addSubview:[mp view]];   
 
    // Play the movie
    [mp play];
  }
}

Beyond removing the notification, we also adjust the status bar, rotate the view, set the frame of the movie player, add the movie player as a subview in the view controller and wrap it all up by asking the movie to play.

Note: MPMoviePlayerViewController is also an option over creating your own view controller as I’ve done here.

Source Code

The easiest way to see all this working is to download the source code and step through the code in the debugger.

Base SDK

The Base SDK is the version of SDK that will be used when compiling your application – the compiler will use the headers and libraries of this specific SDK. For example, in the image below notice that there are only two choices for the Base SDK for both the device and simulator, versions 3.2 and 4.0.

However, we have an issue here, if you build an application with the latest SDK and deploy on a device with an earlier OS, chances are your application will crash if you reference any code in a 4.x API while running the application on a 3.x device. Also, the 3.2 SDK is for the iPad only, so this isn’t an option when deploying to an iPhone or iPod touch.

iPhone OS Deployment Target

To specify which OS version is the minimum that your application will support, you set the deployment target. Your application will then run on this minimum OS as well as all later versions.

This is all well and good, however, the obvious question is how to deploy on an earlier OS version yet take advantage of features for those devices that are running a later OS?

Check for Feature Availability Not OS Version

When targeting an earlier OS as mentioned above, yet you want to take advantage of features of a later OS for devices that support it, you can use the method respondsToSelector to check if the receiver implements or inherits a method that can respond to a specified message. This approach follows Apple’s recommendation to check for availability of features versus a specific OS version.

In the example below the code will check if the object returned by [UIDevice currentDevice] will respond to the selector shown, if so, you can write relevant multi-tasking code:

if ([[UIDevice currentDevice] respondsToSelector:@selector(isMultitaskingSupported)])
{
  // Multi-tasking code for supported devices
}
else
{
  // Devices without multi-tasking support
}

Another time when that you may choose to use respondsToSelector is for cases when the implementation of the same API has changed with a later OS version. I ran into this particular case when writing code for displaying movies using the MPMoviePlayerController. In the 4.x SDK the notifications have changed slightly – in 2.0 to 3.1 MPMoviePlayerContentPreloadDidFinishNotification was the notification you would use to receive notice that a movie was ready to play. With 3.2 (iPad) and later, MPMoviePlayerContentPreloadDidFinishNotification has been deprecated and MPMoviePlayerLoadStateDidChangeNotification has taken its place.

The code example below shows how you may go about using respondsToSelector to figure out which notification you should request based on the whether or not the movie player can return information about its load state:

MPMoviePlayerController *mp = 
   [[MPMoviePlayerController alloc] initWithContentURL:movieURL];
 
// This method is available on 3.2 and greater...
 if ([mp respondsToSelector:@selector(loadState)]) 
{
  // Register to receive notification when load state changed
  // (check for playable, stalled...)
  [[NSNotificationCenter defaultCenter] addObserver:self 
                       selector:@selector(moviePlayerLoadStateChanged:) 
                       name:MPMoviePlayerLoadStateDidChangeNotification 
                       object:nil];
 
}
else
{
  // Register to receive a notification when the movie is ready to play.
  [[NSNotificationCenter defaultCenter] addObserver:self 
                         selector:@selector(moviePreloadDidFinish:) 
                         name:MPMoviePlayerContentPreloadDidFinishNotification 
                         object:nil];
 
}

Check for Function Availability

Beyond working with objects, if you need to check for the availability of a specific function, you do so by comparing the function to NULL. In the example below I check for a function related to creating a PDF-based graphics context (available in 3.2 and later).

if (UIGraphicsBeginPDFContextToFile != NULL)
{
  // The function is available
}

Testing Across OS Versions

Unfortunately, with the upgrade to the latest Xcode (3.2.3) there are no simulators for 3.1.x and earlier OS versions. Although it has always been recommended to test your apps on device, at this point it becomes a necessity.

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userInfo Dictionary

Below I add an observer for MPMoviePlayerContentPreloadDidFinishNotification, which will send a message to the method moviePreloadDidFinish: when a MoviePlayerController object has finished playing:

mp =  [[MPMoviePlayerController alloc] initWithContentURL:movieURL];
 
[[NSNotificationCenter defaultCenter] addObserver:self 
                     selector:@selector(moviePreloadDidFinish:) 
                     name:MPMoviePlayerContentPreloadDidFinishNotification 
                     object:mp];
}

Here’s how to access and print the userInfo dictionary from the notification object:

- (void) moviePlayBackDidFinish:(NSNotification*)notification 
{
  NSDictionary *userInfo = [notification userInfo];
 
  NSLog(@"MPMoviePlayerPlaybackDidFinishReasonUserInfoKey: %@",
    [userInfo objectForKey:@"MPMoviePlayerPlaybackDidFinishReasonUserInfoKey"]);
 
  ...
}

The value of MoviePlayerPlaybackDidFinishReasonUserInfoKey is an NSNumber object which contains an integer value specifying reason the playback finished. The possible range of return values are defined in MPMovieFinishReason, which is an enum type as shown here:

enum {
   MPMovieFinishReasonPlaybackEnded,
   MPMovieFinishReasonPlaybackError,
   MPMovieFinishReasonUserExited
};
typedef NSInteger MPMovieFinishReason;

Pulling all this together, you could write something similar to the following to check if the user stopped playback of the movie:

if ([[userInfo objectForKey:@"MPMoviePlayerPlaybackDidFinishReasonUserInfoKey"] intValue] == MPMovieFinishReasonUserExited)
    NSLog(@"User stopped playback");

object Method

One more handy method within NSNotification is the method object, which will return the object (as type id) that is associated with the notification. For example, check out the code below that sets up the notification, pay attention to the last parameter mp which is assigned to the object parameter.

mp =  [[MPMoviePlayerController alloc] initWithContentURL:movieURL];
 
[[NSNotificationCenter defaultCenter] addObserver:self 
                     selector:@selector(moviePreloadDidFinish:) 
                     name:MPMoviePlayerContentPreloadDidFinishNotification 
                     object:mp];

Within the method called by the selector, you can now access the object passed in by querying the object method:

- (void) moviePlayBackDidFinish:(NSNotification*)notification 
{
  MPMoviePlayerController *mpObject = (MPMoviePlayerController *) [notification object]; 
...

mpObject will point to the mp object defined in the previous code block – using the object method you can retrieve a pointer to the object that made the original notification request.

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