UIAlertView上添加UIActivityIndicatorView提示用戶，「操做正在進行」

代碼：

#import <UIKit/UIKit.h>

#define COOKBOOK_PURPLE_COLOR	[UIColor colorWithRed:0.20392f green:0.19607f blue:0.61176f alpha:1.0f]
#define BARBUTTON(TITLE, SELECTOR) 	[[[UIBarButtonItem alloc] initWithTitle:TITLE style:UIBarButtonItemStylePlain target:self action:SELECTOR] autorelease]

@interface TestBedViewController : UIViewController <UIAlertViewDelegate>
{
	UIAlertView *baseAlert;
}
@end

@implementation TestBedViewController
- (void) performDismiss	
{
    [baseAlert dismissWithClickedButtonIndex:0 animated:NO];
}

- (void) action: (UIBarButtonItem *) item
{
    baseAlert = [[[UIAlertView alloc] initWithTitle:@"Please Wait" message:nil delegate:self cancelButtonTitle:nil otherButtonTitles: nil] autorelease];
    [baseAlert show];

	// Create and add the activity indicator
	UIActivityIndicatorView *aiv = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];
	aiv.center = CGPointMake(baseAlert.bounds.size.width / 2.0f, baseAlert.bounds.size.height - 40.0f);
	[aiv startAnimating];
	[baseAlert addSubview:aiv];
	[aiv release];

	// Auto dismiss after 3 seconds
	[self performSelector:@selector(performDismiss) withObject:nil afterDelay:3.0f];
}

- (BOOL) shouldAutorotateToInterfaceOrientation: (UIInterfaceOrientation) orientation
{
	return YES;
}

- (void) viewDidLoad
{
	self.navigationController.navigationBar.tintColor = COOKBOOK_PURPLE_COLOR;
	self.navigationItem.rightBarButtonItem = BARBUTTON(@"Action", @selector(action:));
}
@end

@interface TestBedAppDelegate : NSObject <UIApplicationDelegate>
@end

@implementation TestBedAppDelegate
- (void)applicationDidFinishLaunching:(UIApplication *)application {	
	UIWindow *window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
	UINavigationController *nav = [[UINavigationController alloc] initWithRootViewController:[[TestBedViewController alloc] init]];
	[window addSubview:nav.view];
	[window makeKeyAndVisible];
}
@end

int main(int argc, char *argv[])
{
	NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
	int retVal = UIApplicationMain(argc, argv, nil, @"TestBedAppDelegate");
	[pool release];
	return retVal;
}

效果以下：