objective-c - IOS：如何使用异步 TBXML 调用刷新 UI

Question

我正在使用 TBXML 解析 http-XML 文件并在 UILabel 和 UIImageView 中显示内容。对 XML 的调用是通过异步请求完成的。

当我查看日志时，succesblock 中的最后一个日志元素会立即打印出来。UILabel 和 UIImageview 中的更改仅在几秒钟后可见。

处理完 XML 后，如何让 IOS 直接刷新 UI？

// Create a success block to be called when the async request completes
TBXMLSuccessBlock successBlock = ^(TBXML *tbxmlDocument) {
    // If TBXML found a root node, process element and iterate all children
    NSLog(@"PROCESSING ASYNC CALLBACK");
    if (tbxmlDocument.rootXMLElement)
        [self traverseElement:tbxmlDocument.rootXMLElement];

    myArticle.Body = [[StringCleaner sharedInstance] cleanedString:myArticle.Body];
   // myArticle.Body = [myArticle.Body stringByConvertingHTMLToPlainText];
    self.articleBody.text = myArticle.Body;
    self.articleBody.numberOfLines= 0;
    self.articleBody.lineBreakMode = UILineBreakModeWordWrap;
    [self.articleBody sizeToFit];

    // set scroll view size
    self.articleBodyScrollView.contentSize = CGSizeMake(self.articleBodyScrollView.contentSize.width, self.articleBody.frame.size.height);

    NSURL *url = [NSURL URLWithString:myArticle.Photo];
    NSData *data = [NSData dataWithContentsOfURL:url];
    if (data != NULL)
    {
        UIImage *image = [UIImage imageWithData:data];
        // articlePhoto = [[UIImageView alloc] initWithImage:image];
        [self.articlePhoto setImage:image];
    }else {
        NSLog(@"no data");
    }

    NSLog(@"FINISHED PROCESSING ASYNC");


    // [self printArticles];
};

// Create a failure block that gets called if something goes wrong
TBXMLFailureBlock failureBlock = ^(TBXML *tbxmlDocument, NSError * error) {
    NSLog(@"Error! %@ %@", [error localizedDescription], [error userInfo]);
};

// tbxml = [[TBXML alloc] initWithURL:[NSURL URLWithString:someXML]];
tbxml = [[TBXML alloc] initWithURL:[NSURL URLWithString:records] 
                           success:successBlock 
                           failure:failureBlock];

Answer 1

听起来您试图更新 UI，但不是在 UI 线程上。将您的 UILabel 和 UIImageView 更新包装到主线程上的 dispatch_async 中，例如：

dispatch_async(dispatch_get_main_queue(), ^
{
 [self.articlePhoto setImage:image];
});