ios - 不要像在iOS 6中那样在iOS 7中工作dispatch_async

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该程序有一部分：

dispatch_sync (dispatch_get_main_queue (), ^ {
    [startBtn setTitle: @ "Loading ..." forState: UIControlStateNormal];
    [self loadImages]; / / loading images - AssesLibrary
});

[self makeCollage];
NSLog (@ "Albums found:% lu", (unsigned long) [assetGroups count]);

从块dispatch_sync程序中出来，我需要首先执行[self loadImages]（数据填充数组）的功能，然后再执行[self makeCollage]。
如果没有dispatch_sync-则仅[self makeCollage]开始填充而不进行进一步处理，并给出错误。

建议如何做

最佳答案

添加 ：

dispatch_queue_t currentQueue=dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_async(currentQueue, ^{

    __block UIImage *image=nil;
    dispatch_sync(currentQueue, ^{

        //download the image here
        image = [self loadImages];

    });

dispatch_sync(dispatch_get_main_queue(), ^{

        //handle the image to the user here on the main queue
        if (image != nil){
            [self makeCollage];
        } else
        {
            NSLog(@"Image isn't downloaded. Nothing to do.");
        }

    });
});

关于ios - 不要像在iOS 6中那样在iOS 7中工作dispatch_async ，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/19674874/