iOS重写系统中的UINavigationController返回按钮的事件

以下主要帮助朋友们监听iOS系统的UINavigationController返回按钮的事件，主要有两种方案

第一种方案就是大家都能想到的，也是最简单的，代码如下：

-(void)viewWillDisappear:(BOOL)animated{
[super viewWillDisappear:animated];
}

因为，点击导航条的返回按钮后，首先触发的事件就是当前页面消失，变得不可见，这确实是一个行之有效的方案。

第二种方案就是重写系统中的UINavigationController返回按钮监听事件，具体代码和实现说明如下：

1.扩展UIviewController
UIViewController+BackButtonHandler.h

#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
UIViewController+BackButtonHandler.m文件

#import "UIViewController+BackButtonHandler.h"

@implementation UIViewController (BackButtonHandler)

@end
2.扩展UINavigationController ,也可以继承 使用

@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(subview.alpha < 1.) {
[UIView animateWithDuration:.25 animations:^{
subview.alpha = 1.;
}];
}
}
}

return NO;
}

@end
3.测试使用

#import "ViewController.h
#import "UIViewController+BackButtonHandler.h"

@implementation ViewController

-(void) viewDidLoad
{
[super viewDidLoad];
self.title =  [NSString stringWithFormat:@"Screen-%d", self.navigationController.viewControllers.count];
self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"Next" style:UIBarButtonItemStylePlain
target:selfaction:@selector(onNextBtn:)];
}

-(void) onNextBtn:(id)sender
{
[self.navigationController pushViewController:[ViewController new] animated:YES];
}

-(BOOL) navigationShouldPopOnBackButton ///在这个方法里写返回按钮的事件处理
{

//这里写要处理的代码
[self.navigationController popViewControllerAnimated:YES];
return YES;//返回NO 不会执行

}

具体怎么选择看个人需要，希望能帮助到各位！