Creating a "loading..." view using iPhone SDK...

Question

How to create that black/gray modal popup kind of view that many apps use, when some long pending operation is in progress?

Like when using location based services, loading a webpage, the screen goes dim and there is a modal view showing a spinning icon "Please wait..."

I've posted a screenshot of what I mean here... http://www.flickr.com/photos/mugunthkumar/3503268688/

Answer 1

This is actually the undocumented (in 2.2.1 anyway) UIProgressHUD. Create one like this:

In your .h:

@interface UIProgressHUD : NSObject 
- (UIProgressHUD *) initWithWindow: (UIView*)aWindow; 
- (void) show: (BOOL)aShow; 
- (void) setText: (NSString*)aText; 
@end

In your .m:

- (void) killHUD: (id)aHUD 
{ 
[aHUD show:NO]; 
[aHUD release]; 
} 

- (void) presentSheet 
{ 
id HUD = [[UIProgressHUD alloc] initWithWindow:[contentView superview]]; 
[HUD setText:@"Doing something slow. Please wait."]; 
[HUD show:YES]; 
[self performSelector:@selector(killHUD:) withObject:HUD afterDelay:5.0]; 
}

Answer 2

If you add a UIView as a subview of the main window it will cover the entire UI. Make it partially transparent and partially translucent and it will look like a popup.

This example shows how to fade the Default.png splash screen, starting with that it's pretty straightforward to add a couple methods to your application delegate (that has a pointer to the main window) to present and dismiss the progress view.

Answer 3

Take a look at the Wordpress iPhone app (http://iphone.wordpress.org/) for an example of how to do this without using any undocumented API's.

Answer 4

If you want to avoid undocumented api you can also take a look at MBProgressHUD. It's similar to UIProgressHUD and even has some additional features.