IOS控件AlertView的使用

alert views are pop-up views that appear over the current view on the iphone.

creating and showing an alert (arc compatible):

    uialertview *alert = [[uialertview alloc] initwithtitle:@"really reset?" message:@"do you really want to reset this game?" delegate:self cancelbuttontitle:@"cancel" otherbuttontitles:nil];
    // optional - add more buttons:
    [alert addbuttonwithtitle:@"yes"];
    [alert show];
for non-arc (retain/release) projects, you must autorelease the alert view:

    uialertview *alert = [[[uialertview alloc] initwithtitle:@"really reset?" message:@"do you really want to reset this game?" delegate:self cancelbuttontitle:@"cancel" otherbuttontitles:nil] autorelease];
    // optional - add more buttons:
    [alert addbuttonwithtitle:@"yes"];
    [alert show];
if you add the uialertviewdelegate protocol to your controller, you can also add the following method which is called after the user dismisses the alert view:

- (void)alertview:(uialertview *)alertview diddismisswithbuttonindex:(nsinteger)buttonindex {
    if (buttonindex == 1) {
        // do stuff
    }
}
button indices start at 0 (for the cancelbutton specified in the alloc/init), and go up by 1 for each addbuttonwithtitle call you add. if you have a lot of alerts, your diddismiss method can keep track of which one is being dismissed if you add the settag call to the alert initialization: [alert settag:23];

    uialertview *alert = [[[uialertview alloc] initwithtitle:@"error" message:@"i'm sorry dave, i'm afraid i can't do that." delegate:self cancelbuttontitle:@"ok" otherbuttontitles:nil] autorelease];
    [alert settag:12];
    [alert show];

... later ...

- (void)alertview:(uialertview *)alertview diddismisswithbuttonindex:(nsinteger)buttonindex {
    if ([alertview tag] == 12) {    // it's the error alert
        if (buttonindex == 0) {     // and they clicked ok.
            // do stuff
        }
    }
}

additional references