iOS 7 自定义Back按钮 与 Pop interactive gesture 问题

1、自定义Back按钮

iOS中很多时候我们都会自定义返回按钮，也是一件easy的事，类似如下：

 // 返回按钮
 1 - (void)showNavBackButton
 {
     UIButton *backButton = [UIButton buttonWithType:UIButtonTypeCustom];
     [backButton addTarget:self action:@selector(backButtonAction:)
          forControlEvents:UIControlEventTouchUpInside];
     [backButton setBackgroundImage:[UIImage imageNamed:@"00_back_button"]
                           forState:UIControlStateNormal];
     [backButton setTitle:kLoc(@"Back") forState:UIControlStateNormal];
     [backButton setTitleEdgeInsets:UIEdgeInsetsMake(, , , )];
     backButton.titleLabel.font = kMediumFont();
     backButton.frame = CGRectMake(, , , );
     self.navigationItem.leftBarButtonItem
     = [[UIBarButtonItem alloc] initWithCustomView:backButton];
 }

但是，这样在iOS7下Pop interactive gesture就不好使了。

这里 Here 有一个解决方法。

但是，测试发现在栈中推入一个controller后，快速向左平滑，将会引起崩溃。

查看崩溃日志，发现如下信息：

nested pop animation can result in corrupted navigation bar

2、解决Pop interactive gesture问题

优化的解决方案是简单的让NavigationController自己成为响应的接受者，最好用一个UINavigationController的子类。

1)在过渡的时候禁用interactivePopGestureRecognizer

2)当新的视图控制器加载完成后再启用，建议使用UINavigationController的子类操作

 // 自定义NavigationController
 1 @interface DCBaseNavigationController ()
 <
 UINavigationControllerDelegate,
 UIGestureRecognizerDelegate
 >
 @end

 @implementation DCBaseNavigationController

 - (void)dealloc
 {
     self.interactivePopGestureRecognizer.delegate = nil;
     self.delegate = nil;

     [super dealloc];
 }

 #pragma mark - View lifecycle

 - (void)viewDidLoad
 {
     [super viewDidLoad];
     // Do any additional setup after loading the view.

     if ([self respondsToSelector:@selector(interactivePopGestureRecognizer)]) {
         self.interactivePopGestureRecognizer.delegate = self;
         self.delegate = self;
     }
 }

 - (void)didReceiveMemoryWarning
 {
     [super didReceiveMemoryWarning];
     // Dispose of any resources that can be recreated.
 }

 #pragma mark - Override

 - (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated
 {
     // Hijack the push method to disable the gesture
     if ([self respondsToSelector:@selector(interactivePopGestureRecognizer)]) {
         self.interactivePopGestureRecognizer.enabled = NO;
     }

     [super pushViewController:viewController animated:animated];
 }

 #pragma mark - UINavigationControllerDelegate

 - (void)navigationController:(UINavigationController *)navigationController
        didShowViewController:(UIViewController *)viewController
                     animated:(BOOL)animate
 {
     if ([navigationController respondsToSelector:@selector(interactivePopGestureRecognizer)]) {
         navigationController.interactivePopGestureRecognizer.enabled = YES;
     }
 }

 @end

3、Pop interactive gesture冲突，造成页面假死问题

我遇到的情况是，Push/Pop页面时，没有立即得到想要的效果，页面没有显出出来，NavigationController的didShowViewController:回调方法也没有调用。

页面布局情况是这样的：视图A，有一个Pan手势；视图B是TabBarController，其ViewControllers都是NavigationController。视图B是视图A的子视图。

后来找到原因是：navigationController的interactive pop手势与视图A的pan手势冲突。

具体原因是：rootViewController加载时，调用了didShowViewController:，设置interactivePopGestureRecognizer可用，其实我们并不需要在root的时候也触发这个手势。所以稍加优化如下：

 // 优化
 1 - (void)navigationController:(UINavigationController *)navigationController
        didShowViewController:(UIViewController *)viewController
                     animated:(BOOL)animate
 {
     if ([navigationController respondsToSelector:@selector(interactivePopGestureRecognizer)]) {
         //if ([[navigationController.viewControllers firstObject] isEqual:viewController]) {
         if ([navigationController.viewControllers count] == ) {
             // Disable the interactive pop gesture in the rootViewController of navigationController
             navigationController.interactivePopGestureRecognizer.enabled = NO;
         } else {
             // Enable the interactive pop gesture
             navigationController.interactivePopGestureRecognizer.enabled = YES;
         }
     }
 }

当前显示的是root时，设置interactivePopGestureRecognizer不可用，非root时设置interactivePopGestureRecognizer可用。

参考文章：http://keighl.com/post/ios7-interactive-pop-gesture-custom-back-button/