内存使用随着图像尺寸的增大而不断增加

Question

I have two large size images in the my view controller. The size of images are approximately 1500 x 1800. When I load that view controller a few times I am getting a memory warning and finally my app crashes. I did observe some memory uses. When I load the view controller my memory use is increased by 15 Mbs each time. I have read about image caching, so to avoid image caching I am not loading image from controller, instead I am loading image in the following way :

  UIImage * image = [[UIImage alloc] initWithContentsOfFile:pathForImageFile1];
  imageView.image = image;
  image = nil;

I have declared image view inside .h file like :

@property (weak, nonatomic) IBOutlet UIImageView *imageView;

By the documentation, If I use load image with initWithContentsOfFile method then image should not be cached and memory should be released once unloading of view happens.

Further I tried to nil image :

-(void)viewDidDisappear:(BOOL)animated
{
  imageView = nil;
}

But there is no difference in memory usage. How can I release the memory used by imageview?

Answer 1

Setting imageView IBOutlet to nil will not unload your imageView because strong reference still remains in imageView 's superview ( subviews array).

Unload image using:

-(void) viewDidDisappear:(BOOL)animated {
  [super viewDidDisappear:animated];
  imageView.image = nil;
}