iOS Memory issue (ARC) when downloading and saving large ammount of images from server

Question

The following code downloads 700+ images from a server with varying sizes, the issue here is that memory (even with ARC) is never released and eventually a memory warning appear

Answer 1

Based on your screenshot, I think the issue is with the NSURL caching rather than the actual NSData objects. Can you try the following:

In your Application Delegate, setup an initial URL cache:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    // Do initial setup
    int cacheSizeMemory = 16*1024*1024; // 16MB
    int cacheSizeDisk = 32*1024*1024; // 32MB
    NSURLCache *sharedCache = [[NSURLCache alloc] initWithMemoryCapacity:cacheSizeMemory diskCapacity:cacheSizeDisk diskPath:@"nsurlcache"];
    [NSURLCache setSharedURLCache:sharedCache];

    // Finish the rest of your didFinishLaunchingWithOptions and head into the app proper
}

Add the following to your Application Delegate:

- (void)applicationDidReceiveMemoryWarning:(UIApplication *)application {
    [[NSURLCache sharedURLCache] removeAllCachedResponses];
}

A cache file will be created:"Library/Caches/your_app_id/nsurlcache"

The link to the Apple example is here: URL Cache

Code not tested but this (or something similar) should sort your problem + plus you can experiment with the cache sizes.

Can you post another screenshot of Allocations in action with this code? I would expect to see memory use stop growing and flatten out.