ios - 即使我使用 GCD，UI 也会卡住

Question

当我从 secondView 返回到 mainView 时，我正在 secondView 的 viewDidDisappear 方法中处理某些内容。问题是，由于应用程序必须执行的工作，我的 mainView 卡住了。

这是我的做法:

-(void)viewDidDisappear:(BOOL)animated
{
    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0ul);

    dispatch_async(queue, ^{

    dbq = [[dbqueries alloc] init];

    [[NSNotificationCenter defaultCenter] postNotificationName:@"abc" object:nil];
    //the notification should start a progressView, but because the whole view gets stuck, I can't see it working, because it stops as soon as the work is done

    dispatch_sync(dispatch_get_main_queue(), ^{

    //work    

    });
});

我做错了什么？ 提前致谢!

Answer 1

您需要在 dispatch_async 中执行您的工作到您的 queue。您目前正在主线程中执行工作(假设 //Work 注释就在它所在的位置)，此外，您正在阻塞工作线程等待这项工作。

尝试稍微重新安排您的 GCD 调用:

-(void)viewDidDisappear:(BOOL)animated
{
    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0ul);

    dbq = [[dbqueries alloc] init];

    [[NSNotificationCenter defaultCenter] postNotificationName:@"abc" object:nil];

    dispatch_async(queue, ^{

        // Perform work here

        dispatch_async(dispatch_get_main_queue(), ^{

           // Update UI here

        });
    });
}