HUD在iOS中不工作

我需要从JSON对象加载一些图像。加载这些图像时，我需要在视图上显示HUD。我试图定义一个像下面这样的HUD

在viewDidLoad方法中定义HUD

MBProgressHUD *hud = [MBProgressHUD showHUDAddedTo:self.view animated:YES];
hud.mode = MBProgressHUDModeIndeterminate;
hud.labelText = @"Loading Images";
[hud show:YES];
[hud showWhileExecuting:@selector(loadJSONData) onTarget:self withObject:nil animated:YES];

-(void)loadJSONData{
   _myObject = [[NSMutableArray alloc] init];

   NSData *jsonSource = [NSData dataWithContentsOfURL:[NSURL URLWithString:url]];

   id jsonObjects = [NSJSONSerialization JSONObjectWithData:
                  jsonSource options:NSJSONReadingMutableContainers error:nil];
   NSArray *dataDic = [jsonObjects objectForKey:@"data"];
   for (NSDictionary *dicData in dataDic) {
      Lawyer *l = [[Lawyer alloc] init];
      dispatch_async(queue, ^{
         NSString *imgUrl = [NSString stringWithFormat:@"myurl",l.imageUrl];
         NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:imgUrl]];
         UIImage *image = [UIImage imageWithData:data];
         dispatch_async(dispatch_get_main_queue(), ^{
           l.uiImage = image;
        });

     });
   [_myObject addObject:[l initFromDictionary:dicData]];
   }
}

加载JSONDATA方法

MBProgressHUD *hud = [MBProgressHUD showHUDAddedTo:self.view animated:YES];
hud.mode = MBProgressHUDModeIndeterminate;
hud.labelText = @"Loading Images";
[hud show:YES];
[hud showWhileExecuting:@selector(loadJSONData) onTarget:self withObject:nil animated:YES];

-(void)loadJSONData{
   _myObject = [[NSMutableArray alloc] init];

   NSData *jsonSource = [NSData dataWithContentsOfURL:[NSURL URLWithString:url]];

   id jsonObjects = [NSJSONSerialization JSONObjectWithData:
                  jsonSource options:NSJSONReadingMutableContainers error:nil];
   NSArray *dataDic = [jsonObjects objectForKey:@"data"];
   for (NSDictionary *dicData in dataDic) {
      Lawyer *l = [[Lawyer alloc] init];
      dispatch_async(queue, ^{
         NSString *imgUrl = [NSString stringWithFormat:@"myurl",l.imageUrl];
         NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:imgUrl]];
         UIImage *image = [UIImage imageWithData:data];
         dispatch_async(dispatch_get_main_queue(), ^{
           l.uiImage = image;
        });

     });
   [_myObject addObject:[l initFromDictionary:dicData]];
   }
}

我的out put显示HUD一秒钟后消失了。没有数据正在加载。我该如何解决这个问题

提前谢谢

使用以下代码：

MBProgressHUD *hud = [[MBProgressHUD alloc] initWithView: self.view];
[self.view addSubview: hud];
hud.labelText = @"Loading Images...";

[hud showAnimated:YES whileExecutingBlock:^{
    [self loadJSONData];
} completionBlock:^{
    // Refresh UI 
}];

---

但要确保，在使用线程执行块时，您必须在主线程上更改所有UI。

您的代码按预期工作

loadJSONData

执行异步请求，使选择器实际完成执行。您应该做的是在方法

loadJSONData

之前显示HUD，然后在以下位置接收数据时将其隐藏：

dispatch_async(dispatch_get_main_queue(), ^{
   l.uiImage = image;
   [MBProgressHUD hideHUDForView:self.view animated:YES];
});

---

虽然我个人会在

loadJSONData

中有一个回调，并在完成块中执行HUD解除。

使用，使用MBProgressHUD要容易得多。.设置一个最小显示时间。很可能loadJSONData运行得很快。在我这样做之后，当我滚动它时，会显示图像。很抱歉，我只是从Xcode复制代码并放在那里。你必须在那里添加方法名。而且，没有加载数据。只加载空表。您向completionBlock添加了什么？让我们来看看。