iOS navigation （pop）返回按钮点击提示框

想了一段时间，还是通过博客来记录自己开发学习的过程，也让自己坚持学习，坚持进步
想下载源码的猛戳这里
本文章主要讲的是，点击系统自带的navigation返回按钮，弹出AlertView，点击确认后，才返回上一个页面，如图所示

下面是第二个界面.m的代码,其中-(void)alertView是在.h中公开的方法，方便在NaviViewController这个类中调用

#import "ViewControllerB.h"

@interface ViewControllerB ()

@end

@implementation ViewControllerB

- (void)viewDidLoad {
    [super viewDidLoad];
    self.title = @"第二页";

}
-(void)alertView
{
    UIAlertController *alertVC = [UIAlertController alertControllerWithTitle:@"返回" message:@"你愿意返回吗" preferredStyle:UIAlertControllerStyleAlert];
    UIAlertAction *cancelAction = [UIAlertAction actionWithTitle:@"取消" style:UIAlertActionStyleCancel handler:nil];

    UIAlertAction *sureAction = [UIAlertAction actionWithTitle:@"确定" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
        [self.navigationController popViewControllerAnimated:YES];
    }];
    [alertVC addAction:cancelAction];
    [alertVC addAction:sureAction];
    [self presentViewController:alertVC animated:YES completion:nil];
}

下面是NaviViewController这个类，继承于UINavigationController，主要在这个类中判断navigation自带的back按钮的点击事件，这里是点击back后弹出alertView，废话不多说，如下代码

#import "NaviViewController.h"
#import "ViewControllerB.h"
@interface NaviViewController ()<UIGestureRecognizerDelegate, UINavigationBarDelegate>
//注意此类在appDelegate方法里面进行配置
@end

@implementation NaviViewController

-(BOOL)navigationBar:(UINavigationBar *)navigationBar shouldPopItem:(UINavigationItem *)item
{
    UIViewController *vc = [self.viewControllers lastObject];
    if ([vc isKindOfClass:[ViewControllerB class]]) {
        [(ViewControllerB *)vc alertView];
        for (UIView *subView in [vc.navigationController.navigationBar subviews]) {//保证取消后左箭头颜色不变
            if ([NSStringFromClass([subView class]) isEqualToString:@"_UINavigationBarBackIndicatorView"]) {
                [UIView animateWithDuration:0.25 animations:^{
                    subView.alpha = 1;
                }];
            }
        }
        return NO;
    }
    return YES;
}


@end

对了在appDelegate中也需要进行配置

@implementation AppDelegate


- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

   _window = [[UIWindow alloc]initWithFrame:[UIScreen mainScreen].bounds];
    _window.backgroundColor = [UIColor whiteColor];
    [_window makeKeyAndVisible];
    //注意NaviViewController是自己写得类
    NaviViewController *navi = [[NaviViewController alloc]initWithRootViewController:[ViewController new]];
    navi.navigationBar.backgroundColor = [UIColor blueColor];
    _window.rootViewController = navi;
    return YES;
}

当然这里没有静止手势右滑返回上一界面，需要这功能的自行百度