iOS 7的手勢滑動返回功能

標籤：

　　現在使用預設範本建立的iOS App都支援手勢返回功能，如果導覽列的返回按鈕是自訂的那麼則會失效，也可以參考這裏手動設定無效。

if ([self.navigationController respondsToSelector:@selector(interactivePopGestureRecognizer)]) {      self.navigationController.interactivePopGestureRecognizer.enabled = NO;  }  

　　如果是因為自訂導覽按鈕而導致手勢返回失效，那麼可以在NavigationController的viewDidLoad函數中添加如下代碼：

- (void)viewDidLoad  {      [super viewDidLoad];      // Do any additional setup after loading the view.            __weak typeof (self) weakSelf = self;      if ([self respondsToSelector:@selector(interactivePopGestureRecognizer)]) {          self.interactivePopGestureRecognizer.delegate = weakSelf;      }  }  

　　這樣寫了以後就可以通過手勢滑動返回上一層了，但是如果在push過程中觸發手勢滑動返回，會導致導覽列崩潰（從日誌中可以看出）。針對這個問題，我們需要在pop過程禁用手勢滑動返回功能，需要實現協議“UINavigationControllerDelegate”

- (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated  {        // fix ‘nested pop animation can result in corrupted navigation bar‘      if ([self respondsToSelector:@selector(interactivePopGestureRecognizer)]) {          self.interactivePopGestureRecognizer.enabled = NO;      }            [super pushViewController:viewController animated:animated];  } - (void)navigationController:(UINavigationController *)navigationController         didShowViewController:(UIViewController *)viewController                      animated:(BOOL)animated  {      if ([navigationController respondsToSelector:@selector(interactivePopGestureRecognizer)]) {          navigationController.interactivePopGestureRecognizer.enabled = YES;      }  }  

　　除了使用系統預設的動畫，還可以使用自訂過渡動畫（豐滿的文檔）：

- (id<UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationController                                    animationControllerForOperation:(UINavigationControllerOperation)operation                                                 fromViewController:(UIViewController *)fromVC                                                   toViewController:(UIViewController *)toVC  {      if (operation == UINavigationControllerOperationPop) {          if (self.popAnimator == nil) {              self.popAnimator = [WQPopAnimator new];          }          return self.popAnimator;      }            return nil;  }    - (id<UIViewControllerInteractiveTransitioning>)navigationController:(UINavigationController *)navigationController                           interactionControllerForAnimationController:(id<UIViewControllerAnimatedTransitioning>)animationController  {      return self.popInteractionController;  }    #pragma mark -     - (void)enablePanToPopForNavigationController:(UINavigationController *)navigationController  {      UIScreenEdgePanGestureRecognizer *left2rightSwipe = [[UIScreenEdgePanGestureRecognizer alloc]                                                           initWithTarget:self                                                           action:@selector(didPanToPop:)];      //[left2rightSwipe setDelegate:self];      [left2rightSwipe setEdges:UIRectEdgeLeft];      [navigationController.view addGestureRecognizer:left2rightSwipe];            self.popAnimator = [WQPopAnimator new];      self.supportPan2Pop = YES;  }    - (void)didPanToPop:(UIPanGestureRecognizer *)panGesture  {      if (!self.supportPan2Pop) return ;            UIView *view = self.navigationController.view;            if (panGesture.state == UIGestureRecognizerStateBegan) {          self.popInteractionController = [UIPercentDrivenInteractiveTransition new];          [self.navigationController popViewControllerAnimated:YES];      } else if (panGesture.state == UIGestureRecognizerStateChanged) {          CGPoint translation = [panGesture translationInView:view];          CGFloat d = fabs(translation.x / CGRectGetWidth(view.bounds));          [self.popInteractionController updateInteractiveTransition:d];      } else if (panGesture.state == UIGestureRecognizerStateEnded) {          if ([panGesture velocityInView:view].x > 0) {              [self.popInteractionController finishInteractiveTransition];          } else {              [self.popInteractionController cancelInteractiveTransition];          }          self.popInteractionController = nil;      }  }  

　　如下這個代理方法是用來提供一個非互動過渡動畫的：

- (id<UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationController                                    animationControllerForOperation:(UINavigationControllerOperation)operation                                                 fromViewController:(UIViewController *)fromVC                                                   toViewController:(UIViewController *)toVC  {      if (operation == UINavigationControllerOperationPop) {          if (self.popAnimator == nil) {              self.popAnimator = [WQPopAnimator new];          }          return self.popAnimator;      }            return nil;  }  

　　而下面這個代理方法則是提供互動式動畫：

- (id<UIViewControllerInteractiveTransitioning>)navigationController:(UINavigationController *)navigationController                           interactionControllerForAnimationController:(id<UIViewControllerAnimatedTransitioning>)animationController  {      return self.popInteractionController;  }  

　　這兩個組合起來使用。首先，我們需要有個動畫：

@interface WQPopAnimator : NSObject <UIViewControllerAnimatedTransitioning>    @end  

　　

#import "WQPopAnimator.h"    @implementation WQPopAnimator    - (NSTimeInterval)transitionDuration:(id <UIViewControllerContextTransitioning>)transitionContext  {      return 0.4;  }    - (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext  {      UIViewController *toViewController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];      UIViewController *fromViewController = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];      [[transitionContext containerView] insertSubview:toViewController.view belowSubview:fromViewController.view];            __block CGRect toRect = toViewController.view.frame;      CGFloat originX = toRect.origin.x;      toRect.origin.x -= toRect.size.width / 3;      toViewController.view.frame = toRect;            [UIView animateWithDuration:[self transitionDuration:transitionContext] animations:^{          CGRect fromRect = fromViewController.view.frame;          fromRect.origin.x += fromRect.size.width;          fromViewController.view.frame = fromRect;                    toRect.origin.x = originX;          toViewController.view.frame = toRect;      } completion:^(BOOL finished) {          [transitionContext completeTransition:![transitionContext transitionWasCancelled]];      }];  }    @end  

　　其次，互動式動畫是通過

UIPercentDrivenInteractiveTransition

　　來維護的，在滑動過程中根據滑動距離來進行更新：

} else if (panGesture.state == UIGestureRecognizerStateChanged) {          CGPoint translation = [panGesture translationInView:view];          CGFloat d = fabs(translation.x / CGRectGetWidth(view.bounds));          [self.popInteractionController updateInteractiveTransition:d];  

　　當手勢結束時要做出收尾動作：

} else if (panGesture.state == UIGestureRecognizerStateEnded) {          if ([panGesture velocityInView:view].x > 0) {              [self.popInteractionController finishInteractiveTransition];          } else {              [self.popInteractionController cancelInteractiveTransition];          }          self.popInteractionController = nil;      }  

　　同樣地，自訂的動畫也會有上面提到的導覽列崩潰問題，也可以通過類似的方法來解決：

- (void)navigationController:(UINavigationController *)navigationController         didShowViewController:(UIViewController *)viewController                      animated:(BOOL)animated  {      if (viewController == self.navigationController.pushingViewController) {          self.supportPan2Pop = YES;          self.navigationController.pushingViewController = nil;      }  

　　補充：位於當前navgationController的第一個（[0]）viewController時需要設定手勢代理，不響應。

 

原文地址：http://blog.csdn.net/jasonblog/article/details/28282147

　　

iOS 7的手勢滑動返回功能