How To Properly Compress UIImages At Runtime

Question

I need to load 4 images for simultaneous editing. When I load them from the users library, the memory exceeds 500mb and crashes.

Here is a log from a raw allocations

Answer 1

The reason you're having crashes and seeing such high memory usage is that you are missing the call to UIGraphicsEndImageContext(); -- so you are leaking memory like crazy.

For every call to UIGraphicsBeginImageContextWithOptions, make sure you have a call to UIGraphicsEndImageContext (after UIGraphicsGetImage*).

Also, you should wrap in @autorelease (I'm presuming you're using ARC), otherwise you'll still have out-of-memory crashes if you are rapidly processing images.

Do it like this:

@autorelease {
  UIGraphicsBeginImageContextWithOptions(...);
  ..
  something = UIGraphicsGetImageFromCurrentImageContext();
  UIGraphicsEndImageContext();
}