防止 leftBarButtonItem navigationItem 显示警报

Posted 2023-03-22

【中文标题】防止 leftBarButtonItem navigationItem 显示警报

【英文标题】：Prevent leftBarButtonItem navigationItem show alert

【发布时间】：2015-04-09 07:25:16

【问题描述】：

我有一个文本编辑视图，我想在文本编辑完毕后返回根视图之前提示用户。

到目前为止我已经尝试过了。

self.navigationItem.leftBarButtonItem.title = @"Back";
self.navigationItem.leftBarButtonItem.tintColor = [UIColor grayColor];


-(void) viewWillDisappear:(BOOL)animated 
    if ([self.navigationController.viewControllers indexOfObject:self]==NSNotFound) 
        // back button was pressed.  We know this is true because self is no longer
        // in the navigation stack.
        UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"Confirm Submission" message:@"Current Job Sheet Incomplete\n Please Confirm Your Submission" delegate:self cancelButtonTitle:@"Submit" otherButtonTitles:@"Cancel", nil];
        alert.tag = 1;
        [alert show];
    
//    [super viewWillDisappear:animated];

虽然这会显示警报，但它不会阻止用户被推送到根视图。

【参考方案1】：

在leftBarButton上添加自定义按钮

UIBarButtonItem *backButton = [[UIBarButtonItem alloc] initWithTitle:@"Back" style: UIBarButtonItemStylePlain target:self action:@selector(navigationBackBtnTap)];
self.navigationItem.leftBarButtonItem = backButton;

-(void)navigationBackBtnTap
         UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"Confirm Submission" message:@"Current Job Sheet Incomplete\n Please Confirm Your Submission" delegate:self cancelButtonTitle:@"Submit" otherButtonTitles:@"Cancel", nil];
         alert.tag = 1;
         [alert show];