iOS 攔截系統導航欄返回按鈕事件

當我們使用了系統的導航欄時，默認點擊返回按鈕是 pop 回上一個界面。但是在有時候，我們需要在點擊導航欄的返回按鈕時不一定要 pop 回上一界面，有時就是要返回到指定的界面

如下是兩種語言的解決辦法：

OC 創建一個 Category

#import <UIKit/UIKit.h>

@protocol BackButtonHandlerProtocol <NSObject>
@optional
// Override this method in UIViewController derived class to handle 'Back' button click
-(BOOL)navigationShouldPopOnBackButton;
@end

@interface UIViewController (BackButtonHandler) <BackButtonHandlerProtocol>

@end

 

#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 {
        // Workaround for iOS7.1. Thanks to @boliva - http://stackoverflow.com/posts/comments/34452906
        for(UIView *subview in [navigationBar subviews]) {
            if(0. < subview.alpha && subview.alpha < 1.) {
                [UIView animateWithDuration:.25 animations:^{
                    subview.alpha = 1.;
                }];
            }
        }
    }

    return NO;
}

@end

在需要攔截的類中重寫navigationShouldPopOnBackButton這個方法即可

 

 

swift 　為了不影響代碼混亂，寫了一個擴展類

import UIKit

/// 導航返回協議
@objc protocol NavigationProtocol {
    /// 導航將要返回方法
    ///
    /// - Returns: true: 返回上一界面， false: 禁止返回
    @objc optional func navigationShouldPopMethod() -> Bool
}

extension UIViewController: NavigationProtocol {
    func navigationShouldPopMethod() -> Bool {
        return true
    }
}

extension UINavigationController: UINavigationBarDelegate, UIGestureRecognizerDelegate {
    
    public func navigationBar(_ navigationBar: UINavigationBar, shouldPop item: UINavigationItem) -> Bool {
        if viewControllers.count < (navigationBar.items?.count)! {
            return true
        }
        var shouldPop = false
        let vc: UIViewController = topViewController!
        if vc.responds(to: #selector(navigationShouldPopMethod)) {
            shouldPop = vc.navigationShouldPopMethod()
        }
        if shouldPop {
            DispatchQueue.main.async {
                self.popViewController(animated: true)
            }
        } else {
            for subview in navigationBar.subviews {
                if 0.0 < subview.alpha && subview.alpha < 1.0 {
                    UIView.animate(withDuration: 0.25) {
                        subview.alpha = 1.0
                    }
                }
            }
        }
        return false
    }
    
    public func gestureRecognizerShouldBegin(_ gestureRecognizer: UIGestureRecognizer) -> Bool {
        if children.count == 1 {
            return false
        } else {
            if topViewController?.responds(to: #selector(navigationShouldPopMethod)) != nil {
                return topViewController!.navigationShouldPopMethod()
            }
            return true
        }
    }
}

 在需要攔截的類中重寫navigationShouldPopMethod這個方法即可