iphone - Received memory warning on setimage

Question

This problem has completely stumped me. This is for iOS 5.0 with Xcode 4.2

What's going on is that in my app I let user select images from their photo album and I save those images to apps document directory. Pretty straight forward.

What I do then is that in one of the viewController.m files I create multiple UIImageViews and I then set the image for the image view from one of the picture that user selected from apps dir. The problem is that after a certain number of UIImage sets I receive a "Received memory warning". It usually happens when there are 10 pictures. If lets say user selected 11 pictures then the app crashes with Error (GBC). NOTE: each of these images are at least 2.5 MB a piece.

After hours of testing I finally narrowed down the problem to this line of code

[button1AImgVw setImage:image];

If I comment out that code. All compiles fine and no memory errors happen. But if I don't comment out that code I receive memory errors and eventually a crash. Also note it does process the whole CreateViews IBAction but still crashes at the end. I cannot do release or dealloc since I am running this on iOS 5.0 with Xcode 4.2

Here is the code that I used. Can anyone tell me what did I do wrong?

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    [self CreateViews];
}

-(IBAction) CreateViews
{
    paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask ,YES);
    documentsPath = [paths objectAtIndex:0]; 

    //here 15 is for testing purposes    
    for (int i = 0; i < 15; i++) 
    {    
        //Lets not get bogged down here. The problem is not here
        UIImageView *button1AImgVw = [[UIImageView alloc] initWithFrame:CGRectMake(10*i, 10, 10, 10)];
        [self.view addSubview:button1AImgVw];

        NSMutableString *picStr1a = [[NSMutableString alloc] init];
        NSString *dataFile1a = [[NSString alloc] init];

        picStr1a = [NSMutableString stringWithFormat:@"%d.jpg", i];
        dataFile1a = [documentsPath stringByAppendingPathComponent:picStr1a];
        NSData *potraitImgData1a =[[NSData alloc] initWithContentsOfFile:dataFile1a];
        UIImage *image = [[UIImage alloc] initWithData:potraitImgData1a];

        // This is causing my app to crash if I load more than 10 images!
    //  [button1AImgVw setImage:image];

//If I change this code to a static image. That works too without any memory problem.
button1AImgVw.image = [UIImage imageNamed:@"mark-yes.png"]; // this image is less than 100KB
        }

        NSLog(@"It went to END!");

    }

This is the error I get when 10 images are selected. App does launch and work

2012-10-07 17:12:51.483 ABC-APP[7548:707] It went to END!
2012-10-07 17:12:51.483 ABC-APP [7531:707] Received memory warning.

App crashes with this error when there are 11 images

2012-10-07 17:30:26.339 ABC-APP[7548:707] It went to END!
(gbc)

Answer 1

This situation (memory warnings and application quitting while attempting to load multiple full resolution UIImages into a view) has attempted to burn me a couple times in my iOS programming career.

You need to make a shrinked down copy of your original image before doing the "setImage" call.

For my own code, I use the "UIImage+Resize" category, the details for which can be found here.

Resize your image to something smaller before inserting into your view, then make sure the full resolution image is released (or set to nil if on ARC) and you should have a happier time of things.

Here is how I do it in my own code:

CGSize buttonSize = CGSizeMake(width, height);
// it'd be nice if UIImage took a file URL, huh?
UIImage * newImage = [[UIImage alloc] initWithContentsOfFile: pathToImage];
if(newImage)
{
    // this "resizedimage" image is what you want to pass to setImage
    UIImage * resizedImage = [newImage resizedImage: buttonSize interpolationQuality: kCGInterpolationLow];
}