Objective_C 导航栏返回按钮点击时间拦截

一、创建一个UIViewController的分类即可：

1、h文件

#import <UIKit/UIKit.h>

@protocol BackButtonHandlerProtocol <NSObject>

@optional

// 重写下面的方法以拦截导航栏返回按钮点击事件，返回 YES 则 pop，NO 则不 pop

-(BOOL)navigationShouldPopOnBackButton;

@end

@interface UIViewController (BackButtonHandler) <BackButtonHandlerProtocol>

// 当前显示控制器

//-(UIViewController*)currentViewController;

@end

2、m文件

#import "UIViewController+BackButtonHandler.h"

@implementation UIViewController (BackButtonHandler)

@end

@implementation UINavigationController (ShouldPopOnBackButton)

- (BOOL)navigationBar:(UINavigationBar *)navigationBar shouldPopItem:(UINavigationItem *)item {

  

    if([self.viewControllers count] < [navigationBar.items count]) {

        return YES;

    }

    BOOL shouldPop = YES;

    UIViewController* vc = [self topViewController];

    if([vc respondsToSelector:@selector(navigationShouldPopOnBackButton)]) {

        shouldPop = [vc navigationShouldPopOnBackButton];

    }

    

    if(shouldPop) {

        dispatch_async(dispatch_get_main_queue(), ^{

            [self popViewControllerAnimated:YES];

        });

    } else {

        // 取消 pop 后，复原返回按钮的状态

        for(UIView *subview in [navigationBar subviews]) {

            if(0. < subview.alpha && subview.alpha < 1.) {

                [UIView animateWithDuration:.25 animations:^{

                    subview.alpha = 1.;

                }];

            }

        }

    }

    return NO;

}

//获取Window当前显示的ViewController

- (UIViewController*)currentViewController{

    //获得当前活动窗口的根视图

    UIViewController* vc = [UIApplication sharedApplication].keyWindow.rootViewController;

    while (1)

    {

        //根据不同的页面切换方式，逐步取得最上层的viewController

        if ([vc isKindOfClass:[UITabBarController class]]) {

            vc = ((UITabBarController*)vc).selectedViewController;

        }

        if ([vc isKindOfClass:[UINavigationController class]]) {

            vc = ((UINavigationController*)vc).visibleViewController;

        }

        if (vc.presentedViewController) {

            vc = vc.presentedViewController;

        }else{

            break;

        }

    }

    return vc;

}  

@end

3、⚠️注意⚠️

到有有自定义导航栏返回按钮self.navigationItem.leftBarButtonItem = UIBarButtonItem时，一定要在leftItem的点击事件方法leftItemClick中添加

func leftItemClick(){

var shouldPop = true;

let tempVC = self.topViewController;

let temp = tempVC?.responds(to: #selector(navigationShouldPopOnBackButton));

if temp != nil && temp! == true {

   shouldPop = (tempVC?.navigationShouldPopOnBackButton())!;

 }

if shouldPop == true {

    self.popViewController(animated: true);

}

}

方可拦截