Message Box (Action Sheet) General

Show a main window message box

Alert View will automatically adjust for landscape orientation

		UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"The username and password entered are not valid"
														message:nil
													   delegate:nil
												cancelButtonTitle:@"OK"
											  otherButtonTitles:nil];
		
;

Show A Message Box

If ActionSheet doesn't auto adjust for landscape orientation check the following:-

[[UIApplication sharedApplication] setStatusBarOrientation:UIInterfaceOrientationLand scapeRight];

needed in applicationDidFinishLaunching?
Supported interface orientations set to landscape in the app plist file?

Using ActionSheet

	UIActionSheet *actionSheet = [[UIActionSheet alloc] initWithTitle:@"A Message To Display"
															delegate:nil
												   cancelButtonTitle:@"OK"
											   destructiveButtonTitle:nil
													otherButtonTitles:nil];
	[actionSheet showInView:[[self view] window]];
	[actionSheet autorelease];

OK Cancel Message Box

In your method that want's to show the action box

	UIActionSheet *actionSheet = [[UIActionSheet alloc] initWithTitle:@"A Message To Display"
															 delegate:self
													cancelButtonTitle:@"Cancel"
											   destructiveButtonTitle:@"OK"
													otherButtonTitles:nil];
	[actionSheet showInView:self.view];

Add the delegate to the classes @interface

@interface #ViewController_iPhone : UIViewController
			<UIActionSheetDelegate>
{

Add the delegate method

//*******************************************
//*******************************************
//********** ACTION SHEET DELEGATE **********
//*******************************************
//*******************************************
- (void)actionSheet:(UIActionSheet *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex
{
	// the user clicked one of the OK/Cancel buttons
	if (buttonIndex == [actionSheet destructiveButtonIndex])
	{
		//----- CLICKED OK -----

	}
	else if (buttonIndex == [actionSheet cancelButtonIndex])
	{
		//----- CLICKED CANCEL -----

	}
}

Multiple Buttons

	UIActionSheet *actionSheet = [[UIActionSheet alloc] initWithTitle:@"A Message To Display"
															 delegate:self
													cancelButtonTitle:@"Cancel"
											   destructiveButtonTitle:nil
													otherButtonTitles:@"Test1",@"Test2",nil];
	[actionSheet showInView:self.view];

In the actionSheet delegate the buttonIndex starts from 0 being the top most button. If there is a destructiveButtonTitle then this is 0 otherwise it is the first otherButtonTitle.

Useful resources

http://www.iphonedevsdk.com/forum/iphone-sdk-development/8478-simple-message-box-popup.html

Creating an about box