Question

第一次使用UIAlertViews，我无法弄清楚为什么这不起作用。当我点击任一按钮时，警报会关闭，但没有 NSLog 输出。我究竟做错了什么？我无法弄清楚。谢谢！

·H

@interface LoginViewController : UIViewController <UIAlertViewDelegate>

@end

的.m

- (IBAction)resetPassword:(UIButton *)sender {

    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Password Reset"
                                                      message:@"A temporary password will be sent to you at the address we have on file."
                                                     delegate:nil
                                            cancelButtonTitle:@"Cancel"
                                        otherButtonTitles:@"Reset Password", nil];
    [alert show];

}

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
    if (buttonIndex == 0) NSLog(@"button 0");
    if (buttonIndex == 1) NSLog(@"button 1");
}

Answer 1

看起来您从未在UIAlertView上设置委托。它应该是：

    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Password Reset"
                                                  message:@"A temporary password will be sent to you at the address we have on file."
                                                 delegate:self
                                        cancelButtonTitle:@"Cancel"
                                    otherButtonTitles:@"Reset Password", nil];

这样，当用户点击按钮时，UIAlertView就可以调用您的方法- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex。

Answer 2

您将delegate设置为零。您需要将其设置为控制器实例，如下所示：

- (IBAction)resetPassword:(UIButton *)sender {

    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Password Reset"
                  message:@"A temporary password will be sent to you at the address we have on file."
                  delegate:self
                  cancelButtonTitle:@"Cancel"
                  otherButtonTitles:@"Reset Password", nil];
    [alert show];

}

如果您从未向UIAlertView提供作为委托的对象，那么实现-alertView:clickedButtonAtIndex:委托方法没什么用。

UIAlertView无法响应按钮事件

2 个答案: