iOS7自定義back按鈕和pop交互手勢

Clambake for iPhone有一個回退按鈕在全部的導航條上.這是一個簡單的沒有文字箭頭.

實現一個自定義按鈕是簡單的.相似這個設置controller 的navigationItem一個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 }

可是這樣在iOS7上 pop手勢交互就很差使了.我發現了一個輕鬆解決的辦法.

經過個人beta測試者,我收到了不少關於pop手勢的崩潰日誌.

我發如今棧中推入一個controller後,快速向左平滑,將會引發崩潰.

換句話說,若是用戶在推入還在進行的時候當即去點擊返回.那麼導航控制器就秀逗了.

我在調試日誌裏面發現這些:

nested pop animation can result in corrupted navigation bar

通過幾個小時的奮鬥和嘗試,我發現能夠緩解這個錯誤:

設置手勢的delegate爲這個導航控制器

就像Stuart Hall在他的帖子說的那樣,分配了一個手勢交互行爲的委託在自定義按鈕顯示的時候.而後,當用戶快速點擊退出的時候,控制器由於手勢發送了一個消息在自己已經被銷燬的時候.

個人解決方案是簡單的讓NavigationController本身成爲響應的接受者.最好用一個UINavigationController的子類.

 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

在轉場/過渡的時候禁用 interactivePopGestureRecognizer

當用戶在轉場的時候觸發一個後退手勢,則各類事件又湊一塊了.導航棧內又成了混亂的.個人解決辦法是,轉場效果的過程當中禁用手勢識別,當新的視圖控制器加載完成後再啓用.再次建議使用UINavigationController的子類操做.

 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