Question

I have an tabbed App using UITabBarController. There are 2 tabs, linked to ViewController1 & ViewController2 respectively. When each view controller loads, it will fetch data from server. Therefore I use MBProgressHUD to show loading status.

However, the behavior currently acts like this: When I switch tab, the app looks like hanged. But after the data is loaded from server, MBProgressHUD flashes a second then disappear, then the view is changed to new tab.

But what I want is: MBProgressHUD shows when the new tab is once touched, and the MBProgressHUD dismisses when the data finishes loading. What did I miss?

Here is the code I use:

- (void)viewDidLoad
{
    [super viewDidLoad];
    MBProgressHUD *hud = [MBProgressHUD showHUDAddedTo:self.view animated:YES];
    hud.labelText = NSLocalizedString(@"Loading", nil);
    // load data from server, parsing XML, etc
    [MBProgressHUD hideHUDForView:self.view animated:YES];
}

UPDATE: Here I have a sample xCode project , you guys can give it a try and tell me what did I miss. [ Download Link ]

Answer 1

I have had this same issue before. The HUD needs access to the main thread to allow it to show. My guess is you are calling it in a nested method that is blocking out the main thread.

Try calling a method that calls your workload on the main thread. This will present your HUD and dismiss when needed.

[HUD showWhileExecuting:@selector(callingMethod) onTarget:self withObject:nil animated:YES];

-(void)callingMethod {
   [self performSelectorOnMainThread:@selector(dataLoadMethod) withObject:nil waitUntilDone:NO];
}