MBProgressHUD Not Displaying Immediately During Segue Transition

As a developer, we’ve all been there - you’re building an app that uses a Split View layout, and you need to display a Modal View full screen after the user taps on a specific cell in the Master View. However, instead of showing a loading indicator or HUD (Loading Indicator), your app takes a few seconds to load the data into the Detail View, during which time the Modal View is not visible.

In this article, we’ll explore why MBProgressHUD isn’t displaying immediately during segue transition and provide a solution that works for both portrait and landscape orientations.

Understanding MBProgressHUD

MBProgressHUD is a popular iOS library used to display a loading indicator on your app. It provides a convenient way to show a HUD with customizable text, font, and animation. However, it requires careful setup and configuration to work correctly.

The Issue: HUD Not Displaying Immediately During Segue Transition

When you call MBProgressHUD.showHUDAddedTo in your didSelectRow method, the HUD is not displayed immediately because of how segue transitions work under the hood. Here’s what happens:

1. When the user taps on a cell, your app performs a segue transition to the Modal View.
2. During this transition, the Modal View takes over the screen, and any other views are hidden or removed from view.
3. The didSelectRow method is called before the Modal View has finished transitioning onto the screen.

As a result, when you call [HUD show:YES], it’s too late - the HUD hasn’t been displayed yet because the Modal View has taken over the screen.

A Solution Using View Controllers

To display the HUD immediately during segue transition, we need to use the viewDidLoad method of the view controller that will be presented as the Modal View. This is where MBProgressHUD’s delegate property comes in handy.

Here’s an updated version of your code:

## Step 1: Create a HUD instance

```markdown
HUD = [[MBProgressHUD alloc] initWithView:self.view];
HUD.labelText=@"Wait...";
self.view HUD;
[HUD setDelegate:self];

Step 2: Show the HUD when needed

To show and hide the HUD, you can use [HUD show:YES] and [HUD hide:YES]. However, be cautious when using this method. If you call [HUD show:YES] before viewDidLoad, it will not work as expected.

Step 3: Hide the HUD in viewDidLayoutSubviews

To ensure the HUD is hidden after the Modal View has finished laying out its subviews, use viewDidLayoutSubviews. This method is called after viewDidLoad, and any views that have been added to the view hierarchy are properly laid out.

- (void)viewDidLayoutSubviews {
    [HUD hide:YES];
}

Step 4: Use [UIView transitionFromView] to animate the HUD transition

To smoothly transition the HUD onto the screen, use [UIView transitionFromView:]. This method allows you to specify a duration and animation type for the transition.

[UIView transitionFromView:self.view
              toView:[HUD view]
               duration:0.5
               options:UIViewAnimationOptionTransitionCrossDissolve
             animations:nil
               completion:^(BOOL finished) {
                   [self HUD];
               }];

Conclusion

In this article, we’ve explored why MBProgressHUD wasn’t displaying immediately during segue transition and provided a solution that works for both portrait and landscape orientations. By using the viewDidLoad method of the view controller that will be presented as the Modal View, we can display the HUD when it’s time to show it.

Additional Tips

• Make sure to hide the HUD in viewDidLayoutSubviews after the Modal View has finished laying out its subviews.
• Use [UIView transitionFromView:] to smoothly transition the HUD onto the screen.
• Be cautious when using [HUD show:YES] before viewDidLoad.

Last modified on 2023-11-06