从UI线程加载图片？

Question

我如何从后台线程上的资源加载图片？

我目前正在这样做,它在我的UI上减慢了很多东西:

image = [NSData dataWithContentsOfFile:imageName];

我宁愿把它加载到后台线程上.

Answer 1

dispatch_queue_t backgroundQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_queue_t mainQueue = dispatch_get_main_queue();
dispatch_async(backgroundQueue,^{
  // background process
  image = [NSData dataWithContentsOfFile:imageName];
  dispatch_async(mainQueue,^{
    // always update GUI from the main thread
    // uiimageview.image = image.... etc
 });
});