CODEWITHSUNDEEP
iosobjective-cmemoryallocation
testoverblaireau
testoverblaireau

Reputation: 189

ImageCaching on IOS

I've some trouble with memory on my app. I've checked Instruments to get more clue about this issue and i've found that 79% of my memory is used by this :

instruments

So i've searched on Google and some people said that is image caching which saved in memory all my images. Maybe it comes from my allocation ?

Here is how i call my images :

info = [InfoModel getInfo:[NSString stringWithFormat:@"%d", self.idEnigme]];

    myImage = [UIImage imageNamed:[NSString stringWithFormat:@"res/img/%@", [info objectForKey:@"path1"]]];
    myImageView = [[UIImageView alloc] initWithImage:myImage];

    myImageView.frame = CGRectMake(0, 200, [[UIScreen mainScreen] bounds].size.width, 400);

    [self.scrollView addSubview:myImageView];

Info is a class where i parse a Json file where are my path to images.

Thanks for helping, this drives me crazy.

Upvotes: 0

Views: 84

Answers (4)

testoverblaireau
testoverblaireau

Reputation: 189

I've found the problem and i solved it. I'll explain you what was the problem, maybe it could help someone.

The real problem was my UIImage init. Initially i allocated my UIImage in method like the following code :

NSString* fileName = [NSString stringWithFormat:@"%@%@%@", name, number, ext];
            UIImage *myImageHeader = [UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:fileName ofType:nil]];
            UIImageView *myImageViewHeader = [[UIImageView alloc] initWithImage:myImageHeader];

            myImageViewHeader.frame = CGRectMake(0, 0, [[UIScreen mainScreen] bounds].size.width, 277);

            [self.scrollView addSubview:myImageViewHeader];

Finally i've decided to create a UIImageview in my .h via a property and to set it in my method, like this :

#.h
@property (weak, nonatomic) IBOutlet UIImageView *headerImage;

#.m
[self.headerImage setImage:[UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:fileName ofType:nil inDirectory:nil]]];

By this way i saved a lot of memory but i still have leaks. So i decided to delete the image in my UIImageView after use :

dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(1.0 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^(void){
            self.headerImage.image = nil;
        });

Now, my app only use 8mb of memory and manage memory correctly.

Thx for helping !

Upvotes: 0

testoverblaireau
testoverblaireau

Reputation: 189

I'm very worried about the following screen. When i launch "Instruments" in Allocations mode, i see every image of my app adding to "Living". I really don't understand how it could be possible... enter image description here

Upvotes: 0

Tiddly
Tiddly

Reputation: 1620

I wouldn't worry about that too much, the UIImage cache is cleared when the app receives a low memory warning. It's all handled automatically, so any images that are no longer in use will be flushed from memory at this point.

So if your app is crashing from running out of memory it is not likely because the OS is caching images that are no longer in use.

You can handle your own caching of images by using initWithData instead of imageNamed but I doubt this solution will help you.

Upvotes: 1

Jack
Jack

Reputation: 16865

iOS automatically caches your image for future use when you call imageNamed:

As discussed in a few places, including here:Does UIImageView cache images?

You can get around this caching if you know you are only going to create it once by using

[UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:fileName ofType:nil]]

instead

Upvotes: 1

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