UIActivityIndi​​catorView 没有在 UICollectionViewCell 中旋转 [英] UIActivityIndicatorView not spinning in UICollectionViewCell

问题描述

我的收藏视图底部加载了一个自定义单元格.它唯一的工作是显示一个活动指示器视图——这发生在应用程序进行新的工作调用时.

I have a custom cell that is loaded at the bottom of my collection view. Its only job is to display an activity indicator view - which happens while the app is making a new work call.

所以我像这样将它添加到单元格中:

So I added it to the cell like so:

BBLoaderCell *loaderCell = [collectionView dequeueReusableCellWithReuseIdentifier:@"LoaderCell" forIndexPath:indexPath];


UIActivityIndicatorView * activityIndicator = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhite];
activityIndicator.hidesWhenStopped = YES;
activityIndicator.hidden = NO;
activityIndicator.center = loaderCell.imageView.center;
activityIndicator.tag = 10;

[loaderCell.imageView addSubview:activityIndicator];

    [activityIndicator startAnimating];
    return loaderCell;

这在我视图的最后一个单元格中显示了一个活动指示器 - 但是它没有旋转.有什么想法吗?

This shows an activity indicator in the last cell of my view - however it does not spin. Any ideas?

找到解决方案

根据评论 - 这是一个线程问题.我还接受了将代码移动到单元格的自定义 nib 文件的建议.

As per comments - it was a threading issue. I also took the suggestion to move the code to the custom nib file for the cell.

这里是重构的代码:

BBLoaderCell *loaderCell = [collectionView dequeueReusableCellWithReuseIdentifier:@"LoaderCell" forIndexPath:indexPath];
    loaderCell.backgroundColor = [UIColor clearColor];

     if (self.loadingMore == NO){
        dispatch_async(dispatch_get_main_queue(), ^{
            activityIndicator.hidden = YES;
            [loaderCell.spinner stopAnimating];
        });
    }
     else if (self.loadingMore == YES){
    dispatch_async(dispatch_get_main_queue(), ^{
        activityIndicator.hidden = NO;
        [loaderCell.spinner startAnimating];
    });
    }

    return loaderCell;

这是我需要的工作.

谢谢各位！

推荐答案

我认为这可能与线程有关(例如，主线程上的 UI 尚未准备好为指示器设置动画).您可以尝试以下方法:

I think this might have something to do with threading (eg. the UI on main thread not being ready to animate the indicator). You could try something like the following:

[activityIndi​​cator performSelector:@selector(startAnimating:) withObject:nil afterDelay:1];

不过，这只是一个可能的建议，您应该尝试不同的变体，并检查哪个变体正确且及时地将动画强制到主线程上.另一种变化:

This is just a possible suggestion though, you should try different variations and check which one forces the animation onto the main thread correctly and in a timely matter. Another variation:

dispatch_async(dispatch_get_main_queue(), ^{
    [activityIndicator startAnimating];
});

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