ios - 如何在 block 内分配 UIimage

Question

我正在向 URL 发出下载图像的请求。我将其作为 NSData 对象接收，但当我尝试将其转换为 UIimage with imageWithData: 时，UIImage 未加载。这是我的代码

__block ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];
__weak typeof(request)weakRequest = request;
__block UIImage * imager;
__block NSData * image;
[request setCompletionBlock:^{
    [self parseXMLFileAtFileId:[weakRequest responseData]];
    if (!files){
        cell.correctImage.image = [UIImage imageNamed:@"sidebarPlaceholder"];
    }
    else{

        NSURL *url = [NSURL URLWithString:[self downloading:[files objectAtIndex:0]]];
        __block ASIHTTPRequest *requester = [ASIHTTPRequest requestWithURL:url];

        __weak typeof(request)weakRequesting = requester;
        [requester setCompletionBlock:^{
            image =  [weakRequesting responseData];
            imager = [UIImage imageWithData:image];
            cell.correctImage.image = imager;
            [cell layoutIfNeeded];
        }];

        [requester startAsynchronous];
    }
}];

以前，我通过明确说明 UIImageView 的大小来实现它，但这应该由 UITableviewCell 来处理。如何显示图像？

Answer 1

尝试在主线程中运行这些代码块，因为看起来您正在尝试在后台线程中设置图像和更新布局。在

之后立即使用以下 NSThread 方法

UIImage *imager = [UIImage imageWithData:image]

[self performSelectorOnMainThread:@selector(updateImage:) withObject:imager waitUntilDone:false];

//定义更新图像的方法

- (void)updateImage: (UIImage *)paramImage {
    cell.correctImage.image = paramImage;
    [cell layoutIfNeeded];
}