iOS7自定義back按鈕和pop交互手勢

Clambake for iPhone有一個回退按鈕在所有的導航條上.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.類似這個設置controller 的navigationItem一個leftBarButtonItem.

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

- (UIBarButtonItem *)backButton
{
  UIImage *image = [UIImage imageNamed:@"back_button"];
  CGRect buttonFrame = CGRectMake(0, 0, 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;
}

但是這樣在iOS7上 pop手勢交互就不好使了.我發現了一個輕松解決的辦法.

通過我的beta測試者,我收到了很多關於pop手勢的崩潰日志.

我發現在棧中推入一個controller后,快速向左平滑,將會引起崩潰.

換句話說,如果用戶在推入還在進行的時候立即去點擊返回.那么導航控制器就秀逗了.

我在調試日志里面發現這些:

nested pop animation can result in corrupted navigation bar

經過幾個小時的奮斗和嘗試,我發現可以緩解這個錯誤:

設置手勢的delegate為這個導航控制器

就像Stuart Hall在他的帖子說的那樣,分配了一個手勢交互行為的委托在自定義按鈕顯示的時候.然后,當用戶快速點擊退出的時候,控制器因為手勢發送了一個消息在本身已經被銷毀的時候.

我的解決方案是簡單的讓NavigationController自己成為響應的接受者.最好用一個UINavigationController的子類.

@interface CBNavigationController : UINavigationController <UIGestureRecognizerDelegate>
@end

@implementation CBNavigationController

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

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

@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后退手勢,則各種事件又湊一塊了.導航棧內又成了混亂的.我的解決辦法是,轉場效果的過程中禁用手勢識別,當新的視圖控制器加載完成后再啟用.再次建議使用UINavigationController的子類操作.

@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