Programming iOS 6, 3rd Edition

Alert View

The basic method for constructing an alert view (UIAlertView) is initWithTitle:message:delegate:cancelButtonTitle:otherButtonTitles:. The method for making a constructed alert view appear onscreen is show. The alert is automatically dismissed as soon as the user taps any button. Here’s an example (Figure 26-1):

UIAlertView* alert = [[UIAlertView alloc] initWithTitle:@"Not So Fast!"
    message:@"Do you really want to do this tremendously destructive thing?"
    delegate:self cancelButtonTitle:@"Yes"
    otherButtonTitles:@"No", @"Maybe", nil];
[alert show];

Figure 26-1. An alert view

The otherButtonTitles parameter is of indefinite length, so it must be either nil or a nil-terminated list (not an array!) of strings. The cancel button needn’t be titled “Cancel”; it is drawn darker than the other buttons and comes last in a column of buttons, as you can see from Figure 26-1. If there are more than two otherButtonTitles and a nil cancelButtonTitle, the last of the otherButtonTitles is drawn as if it were a cancel button; this code, too, produces Figure 26-1:

UIAlertView* alert = [[UIAlertView alloc] initWithTitle:@"Not So Fast!"
    message:@"Do you really want to do this tremendously destructive thing?"
    delegate:self cancelButtonTitle:nil
    otherButtonTitles:@"No", @"Maybe", @"Yes", nil];

If an alert view is to contain a text field, it probably should have at most one or two buttons, with short ...