How to create an alert box in iphone?

Question

I would like to make an alert type box so that when the user tries to delete something, it says, "are you sure" and then has a yes or no for if they are sure. What would be the best way to do this in iphone?

Answer 1

A UIAlertView is the best way to do that. It will animate into the middle of the screen, dim the background, and force the user to address it, before returning to the normal functions of your app.

You can create a UIAlertView like this:

UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Wait" message:@"Are you sure you want to delete this.  This action cannot be undone" delegate:self cancelButtonTitle:@"Delete" otherButtonTitles:@"Cancel", nil]; [alert show]; 

That will display the message.

Then to check whether they tapped delete or cancel, use this:

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex{     if (buttonIndex == 0){         //delete it     } } 

Make sure in your header file (.h), you include the UIAlertViewDelegate by putting <UIAlertViewDelegate>, next to whatever your class inherits from (ie. UIViewController or UITableViewController, etc.)

For more infomation on all the specifics of UIAlertViews check out Apple's Docs Here

Hope that helps

Answer 2

The post is quite old, but still a good question. With iOS 8 the answer has changed. Today you'd rather use 'UIAlertController' with a 'preferredStyle' of 'UIAlertControllerStyle.ActionSheet'.

A code like this (swift) that is bound to a button:

@IBAction func resetClicked(sender: AnyObject) {     let alert = UIAlertController(         title: "Reset GameCenter Achievements",         message: "Highscores and the Leaderboard are not affected.\nCannot be undone",         preferredStyle: UIAlertControllerStyle.ActionSheet)     alert.addAction(         UIAlertAction(             title: "Reset Achievements",             style: UIAlertActionStyle.Destructive,             handler: {                 (action: UIAlertAction!) -> Void in                 gameCenter.resetAchievements()             }         )     )     alert.addAction(         UIAlertAction(             title: "Show GameCenter",             style: UIAlertActionStyle.Default,             handler: {                 (action: UIAlertAction!) -> Void in                 self.gameCenterButtonClicked()             }         )     )     alert.addAction(         UIAlertAction(             title: "Cancel",             style: UIAlertActionStyle.Cancel,             handler: nil         )     )     if let popoverController = alert.popoverPresentationController {         popoverController.sourceView = sender as UIView         popoverController.sourceRect = sender.bounds     }     self.presentViewController(alert, animated: true, completion: nil) } 

would produce this output:

EDIT: The code crashed on iPad, iOS 8+. If added the necessary lines as described here: on another stack overflow answer