iphone - 使用 UIAlertView 检测按钮点击

Question

我正在尝试在按下按钮时调用电话并发出警报。我用这个:

-(IBAction)Add { 
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle: @"add button pressed"
                                                    message:@"Add to record"
                                                   delegate:nil     
                                          cancelButtonTitle:@"Cancel" 
                                          otherButtonTitles:@"OK", nil   ];
    [alert show];
    [alert release];    
} 

好的，没问题，出现了两个按钮，确定和取消。现在我想检测我使用的是哪个按钮:

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex {
    // the user clicked one of the OK/Cancel buttons
    if (buttonIndex == 0)
    {
       //just to show its working, i call another alert view
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle: @"OK WORKIng well"
                                                        message:@"no error"                                                                                                            delegate:nil 
                                              cancelButtonTitle:@"IWORKS" 
                                              otherButtonTitles:@"NO PRB", nil];
        [alert show];
        [alert release];    


    }
    else
    {
        NSLog(@"cancel");       
    }
}

现在问题来了。我无法检测到按下了哪个按钮；第二个警报 View 不显示。我已经检查了代码几次，似乎没有任何问题。也没有错误/警告。

Answer 1

要检测按钮点击，警报 View 必须有一个关联的委托(delegate)，例如

UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"add button pressed"
                                                message:@"Add to record"
                                               delegate:self    // <------
                                      cancelButtonTitle:@"Cancel"
                                      otherButtonTitles:@"OK", nil];