iOS7自定义back按钮和pop交互手势

Clambake for iPhone有一个回退按钮在所有的导航条上.这是一个简单的没有文字箭头.

实现一个自定义按钮是简单的.类似这个设置controller 的navigationItem一个leftBarButtonItem.

 - (void)viewDidLoad
 {
   self.navigationItem.leftBarButtonItem = [self backButton];
 }

 - (UIBarButtonItem *)backButton
 {
   UIImage *image = [UIImage imageNamed:@"back_button"];
   CGRect buttonFrame = CGRectMake(, , image.size.width, image.size.height);

   UIButton *button = [[UIButton alloc] initWithFrame:buttonFrame];
   [button addTarget:self action:@selector(backButtonPressed) forControlEvents:UIControlEventTouchUpInside];
   [button setImage:[UIImage imageNamed:normalImage] forState:UIControlStateNormal];

   UIBarButtonItem *item; = [[UIBarButtonItem alloc] initWithCustomView:button];

   return item;
 }

但是这样在iOS7上 pop手势交互就不好使了.我发现了一个轻松解决的办法.

通过我的beta测试者,我收到了很多关于pop手势的崩溃日志.

我发现在栈中推入一个controller后,快速向左平滑,将会引起崩溃.

换句话说,如果用户在推入还在进行的时候立即去点击返回.那么导航控制器就秀逗了.

我在调试日志里面发现这些:

nested pop animation can result in corrupted navigation bar

经过几个小时的奋斗和尝试,我发现可以缓解这个错误:

设置手势的delegate为这个导航控制器

就像Stuart Hall在他的帖子说的那样,分配了一个手势交互行为的委托在自定义按钮显示的时候.然后,当用户快速点击退出的时候,控制器因为手势发送了一个消息在本身已经被销毁的时候.

我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.

 @interface CBNavigationController : UINavigationController <UIGestureRecognizerDelegate>
 @end

 @implementation CBNavigationController

 - (void)viewDidLoad
 {
   __weak CBNavigationController *weakSelf = self;

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

 @end

在转场/过渡的时候禁用 interactivePopGestureRecognizer

当用户在转场的时候触发一个后退手势,则各种事件又凑一块了.导航栈内又成了混乱的.我的解决办法是,转场效果的过程中禁用手势识别,当新的视图控制器加载完成后再启用.再次建议使用UINavigationController的子类操作.

 @interface CBNavigationController : UINavigationController <UINavigationControllerDelegate, UIGestureRecognizerDelegate>
 @end

 @implementation CBNavigationController

 - (void)viewDidLoad
 {
   __weak CBNavigationController *weakSelf = self;

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

 // Hijack the push method to disable the gesture

 - (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated
 {
   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
 {
   // Enable the gesture again once the new controller is shown

   if ([self respondsToSelector:@selector(interactivePopGestureRecognizer)])
     self.interactivePopGestureRecognizer.enabled = YES;
 }

 @end