iOS7自定义back按钮和pop交互手势

Clambake for iPhone有一个回退按钮在全部的导航条上.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.相似这个设置controller 的navigationItem一个leftBarButtonItem.

 1 - (void)viewDidLoad
 2 {
 3   self.navigationItem.leftBarButtonItem = [self backButton];
 4 }
 5 
 6 - (UIBarButtonItem *)backButton
 7 {
 8   UIImage *image = [UIImage imageNamed:@"back_button"];
 9   CGRect buttonFrame = CGRectMake(0, 0, image.size.width, image.size.height);
10 
11   UIButton *button = [[UIButton alloc] initWithFrame:buttonFrame];
12   [button addTarget:self action:@selector(backButtonPressed) forControlEvents:UIControlEventTouchUpInside];
13   [button setImage:[UIImage imageNamed:normalImage] forState:UIControlStateNormal];
14 
15   UIBarButtonItem *item; = [[UIBarButtonItem alloc] initWithCustomView:button];
16 
17   return item;
18 }

可是这样在iOS7上 pop手势交互就很差使了.我发现了一个轻松解决的办法.

经过个人beta测试者,我收到了不少关于pop手势的崩溃日志.

我发如今栈中推入一个controller后,快速向左平滑,将会引发崩溃.

换句话说,若是用户在推入还在进行的时候当即去点击返回.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

通过几个小时的奋斗和尝试,我发现能够缓解这个错误:

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.而后,当用户快速点击退出的时候,控制器由于手势发送了一个消息在自己已经被销毁的时候.

个人解决方案是简单的让NavigationController本身成为响应的接受者.最好用一个UINavigationController的子类.

 1 @interface CBNavigationController : UINavigationController <UIGestureRecognizerDelegate>
 2 @end
 3 
 4 @implementation CBNavigationController
 5 
 6 - (void)viewDidLoad
 7 {
 8   __weak CBNavigationController *weakSelf = self;
 9 
10   if ([self respondsToSelector:@selector(interactivePopGestureRecognizer)])
11   {
12     self.interactivePopGestureRecognizer.delegate = weakSelf;
13   }
14 }
15 
16 @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,则各类事件又凑一块了.导航栈内又成了混乱的.个人解决办法是,转场效果的过程当中禁用手势识别,当新的视图控制器加载完成后再启用.再次建议使用UINavigationController的子类操做.

 1 @interface CBNavigationController : UINavigationController <UINavigationControllerDelegate, UIGestureRecognizerDelegate>
 2 @end
 3 
 4 @implementation CBNavigationController
 5 
 6 - (void)viewDidLoad
 7 {
 8   __weak CBNavigationController *weakSelf = self;
 9 
10   if ([self respondsToSelector:@selector(interactivePopGestureRecognizer)])
11   {
12     self.interactivePopGestureRecognizer.delegate = weakSelf;
13     self.delegate = weakSelf;
14   }
15 }
16 
17 // Hijack the push method to disable the gesture
18 
19 - (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated
20 {
21   if ([self respondsToSelector:@selector(interactivePopGestureRecognizer)])
22     self.interactivePopGestureRecognizer.enabled = NO;
23 
24   [super pushViewController:viewController animated:animated];
25 }
26 
27 #pragma mark UINavigationControllerDelegate
28 
29 - (void)navigationController:(UINavigationController *)navigationController
30        didShowViewController:(UIViewController *)viewController
31                     animated:(BOOL)animate
32 {
33   // Enable the gesture again once the new controller is shown
34 
35   if ([self respondsToSelector:@selector(interactivePopGestureRecognizer)])
36     self.interactivePopGestureRecognizer.enabled = YES;
37 }
38 
39 
40 @end