Comments on: Images and Caching

By: Rev John

Rev John — Sat, 16 Jul 2011 13:31:01 +0000

HI, I’m having the same problem with UIImage’s not releasing. I’m generating UIImages with a bit-bucket, creating them on the fly and swapping the UIImageView’s image. Is there a way to edit the UIImageView’s Image directly? (ie. change the color of a specific pixel, without removing the UIImage from the UIImageView, and get it to redraw.) Currently, I’m flushing the UIImage, making a new one, and assigning it to the UIImageView. This works. Shows no MemLeaks. But on the iPhone (3Gs) after about 100 image replacements, CRASHES. Cache’n issue? The memory summation seems to be hitting the phone’s limit if cache not releasing, however, Simulator does not show memory consumption with each image swap. Stays flatlined without leaks.

Note: topologyImage array is the RGBA pixel-bucket. The REF variables are not released. Every attempt to do so, crashes next call. Without, Instruments reports no leaks.

Make room for me on the imageNamed:bandwagon. However, imageWithCGImage seems to have the same cache’n nightmare. Any alternatives?

=========

CGColorSpaceRef colorSpaceRef=CGColorSpaceCreateDeviceRGB();
CGBitmapInfo bitmapInfo = kCGBitmapByteOrderDefault | kCGImageAlphaLast;
CGColorRenderingIntent renderingIntent=kCGRenderingIntentDefault;
CGDataProviderRef provider=CGDataProviderCreateWithData(NULL,topologyImage,(I*I*4),NULL);
CGImageRef imageRef=CGImageCreate(I,I,8,4*8,4*I,colorSpaceRef,bitmapInfo,provider,NULL,false,renderingIntent);

UIImage *img=[UIImage imageWithCGImage:imageRef];
if( IMG[NDXtopo].vw ) {
[IMG[NDXtopo].vw setImage:img];
}
else {
IMG[NDXtopo].vw=[[UIImageView alloc] initWithImage:img];
[master.view addSubview:IMG[NDXtopo].vw];
}

By: Basri

Basri — Tue, 15 Feb 2011 06:54:17 +0000

Do you have to release the image using the second method like this?

NSString* imagePath = [[NSBundle mainBundle] pathForResource:@”inbox” ofType:@”png”];
UIImage *inbox = [UIImage imageWithContentsOfFile:imagePath];
UIImageView *inboxView = [[UIImageView alloc] initWithImage:inbox];

//Do somthing

[inbox release];
[inboxView release];

NSString* imagePath = [[NSBundle mainBundle] pathForResource:@”inbox” ofType:@”png”];
UIImage *inbox = [[UIImage alloc] imageWithContentsOfFile:imagePath];
UIImageView *inboxView = [[UIImageView alloc] initWithImage:inbox];

//Do somthing

[inbox release];
[inboxView release];

By: Paul van Dijk

Paul van Dijk — Fri, 29 May 2009 07:46:09 +0000

Thank you, im working with more than 100 1700×1200 jpg’s in my app and had memory issues.
This seems to fix the problem.

Thanks very much!!!

By: Roger Nolan

Roger Nolan — Fri, 29 May 2009 07:10:26 +0000

John,

You’ve joined a bandwagon complaining about imageNamed. Do you actually have some insight into why the performance is so bad? Does the imageNamed cache ignore memory warnings?

I’ve created a SO question for any answers.