导航栏后退按钮的操作 [英] Action to Navigation bar back button

问题描述

我想在用户单击后退"按钮时显示带有确认"的警报.这就是我要添加操作的方式.

I want to show an alert with Confirmation when user clicks on back button. This is how I'm trying to add action.

self.navigationItem.hidesBackButton = true
let newBackButton = UIBarButtonItem(title: "<", style: UIBarButtonItemStyle.plain, target: self, action: #selector(ViewController.save(sender:)))
self.navigationItem.leftBarButtonItem = newBackButton

这工作正常，但是我想要默认的后退按钮图像而不是自定义标题.该怎么做?

This is working fine but I want the default back button image in it and not the custom title. How to do that ?

我也尝试了以下代码:

self.navigationItem.backBarButtonItem?.action = #selector(ViewController.save(sender:))

...但是也没有执行该动作.

...but the action is not performed, too.

推荐答案

这可能会有所帮助.这不会覆盖后退动作，但是您可以执行其他任务.

This might help. This wont override back action, but you can do additional task.

客观c

-(void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];
    if(self.isMovingFromParentViewController)
    {
        //On click of back or swipe back
    }
    if(self.isBeingDismissed)
    {
        //Dismissed
    }
    NSLog(@"%d",self.isBeingDismissed);
    NSLog(@"%d",self.isMovingFromParentViewController);
}

迅速

override func viewWillDisappear(_ animated: Bool)
{
    super.viewWillDisappear(animated);
    if self.isMovingFromParentViewController
    {
        //On click of back or swipe back
    }
    if self.isBeingDismissed
    {
        //Dismissed
    }
}

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