Question

My app crashes when I set the image-property on a UIImageView three times in a row (sometimes two times is enough). A few times I’ve seen a memory warning before the app closes, but most of the times it just collapses. The app does not crash in the simulator, so I’m quite sure it is a memory problem.

Here’s the code I use when setting the image property:

-(void)changeBgPictureTo:(UIImage *)img
{
    [self.backgroundImage setImage:img];
}

The UIImages is allocated with the [UIImage imageWithData:] method:

[UIImage imageWithData:[NSData dataWithContentsOfFile:[[NSBundle mainBundle] pathForResource:fileName ofType:type]]];

The image is set correctly the first two times, but crashes on the third time. It has nothing to do with a specific image file. I’ve tried with 10 different images and it makes no difference.

How do I make the UIImageView unload previous loaded images?

EDIT:
Okay, I’ve been asked for the whole code so here it goes:

I’m working with a class which looks like this:

@interface MyImage : NSObject
{
    UIImage* image;
    int imgId;
    NSArray* colors; //contains 'UIColor' objects.
}

@property (nonatomic, retain) UIImage* image;
@property (nonatomic, retain) NSArray* colors;
@property (nonatomic, readwrite) int imgId;

-(id)initWithFileName:(NSString*)fileName withType:(NSString*)type andId:(int)imgId andColors:(NSArray*)colorArray;

@end

Here is the init implementation:

-(id)initWithFileName:(NSString*)fileName withType:(NSString*)type andId:(int)imageId andColors:(NSArray*)colorArray
{
     self = [super init];

     if (self)
     {
         self.colors = [NSArray arrayWithArray:colorArray]; 
         self.imgId = imageId;
         self.image = [UIImage imageWithData:[NSData dataWithContentsOfFile:[[NSBundle mainBundle] pathForResource:fileName ofType:type]]];
     }   

return self;

}

I have a datacontroller which has a list of ‘MyImage’ objects which is added in a loop with this call:

[self.myImages addObject:[[MyImage alloc] initWithFileName:[NSString stringWithFormat:@"0000%d", i] withType:@"jpg" andId:i andColors:colors]];

I have 9 images which is named 00001.jpg, 00002.jpg, ….., 00008.jpg.

This data controller has a method like this:

-(MyImage *)getImageWithId:(int)imgId
{
    for (MyImage* img in self.myImages)
    {
        if (img.imgId == imgId)
            return img;
    }
    return nil;
}

The getImageWithId method is called like this:

-(void)btnPushed:(id)sender
{
     [self.delegate changeBgPictureTo:[self.imgDataController getImageWithId:((UIButton*)sender).tag]];    
}  

The changeBgPictureTo method is the method which makes the setting of the image-property:

-(void)changeBgPictureTo:(MyImage *)img
{
    NSLog(@"Setting image: %d", img.imgId);
    [self.backgroundImage setImage:img.image];    
}

The log prints “Setting image: 0000X:” three times, but crashes shortly after the third print.

Answer 1

Instead of storing the UIImage object inside MyObject class,try storing only the filename of the file.

@interface MyImage : NSObject 
{
    NSString *fileName;//UIImage* image;
    int imgId;
    NSArray* colors; //contains 'UIColor' objects.
}

@property (nonatomic, retain) NSString *fileName;//@property (nonatomic, retain) UIImage* image;
@property (nonatomic, retain) NSArray* colors;
@property (nonatomic, readwrite) int imgId;

-(id)initWithFileName:(NSString*)fileName withType:(NSString*)type andId:(int)imgId andColors:(NSArray*)colorArray;

and implementation

-(id)initWithFileName:(NSString*)fileName withType:(NSString*)type andId:(int)imageId   andColors:(NSArray*)colorArray
{
     self = [super init];

     if (self)
     {
         self.colors = [NSArray arrayWithArray:colorArray]; 
         self.imgId = imageId;
         //self.image = [UIImage imageWithData:[NSData dataWithContentsOfFile:[[NSBundle mainBundle] pathForResource:fileName ofType:type]]];
         self.fileName = [[NSBundle mainBundle] pathForResource:fileName ofType:type]];
      }   
      return self;
 }

then in function

 -(void)changeBgPictureTo:(MyImage *)img   
 {
    NSLog(@"Setting image: %d", img.imgId);
    //[self.backgroundImage setImage:img.image];    
    UIImage *img = [UIImage imageWithContentsOfFile:[img fileName]];
    [self.backgroundImage setImage:img];
 }