好的，所以我终于找到了问题所在.

Ok so I finally figured out the problem.

正如我所说，我正在使用一些后台线程来执行图像更新，解决方案是将其添加为自动释放池，如下所示:

As I said I was using some background thread to perform the image update, the solution was to add it as a autorelease pool as following:

   @autoreleasepool {
        [self.delegate performSelectorOnMainThread:@selector(updateImage:) withObject:[self fetchImage] waitUntilDone:NO];
    }