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iOS UINavigationController的iOS 7的手势滑动返回功能

2016-01-18 00:46 567 查看
现在使用默认模板创建的iOS App都支持手势返回功能,如果导航栏的返回按钮是自定义的那么则会失效,也可以参考这里手动设置无效。

[cpp] view
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if ([self.navigationController respondsToSelector:@selector(interactivePopGestureRecognizer)]) {  

    self.navigationController.interactivePopGestureRecognizer.enabled = NO;  

}  

如果是因为自定义导航按钮而导致手势返回失效,那么可以在NavigationController的viewDidLoad函数中添加如下代码:

[cpp] view
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- (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;  

    }  

}  

这样写了以后就可以通过手势滑动返回上一层了,但是如果在push过程中触发手势滑动返回,会导致导航栏崩溃(从日志中可以看出)。针对这个问题,我们需要在pop过程禁用手势滑动返回功能:

[cpp] view
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- (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];  

}  

[cpp] view
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- (void)navigationController:(UINavigationController *)navigationController  

       didShowViewController:(UIViewController *)viewController  

                    animated:(BOOL)animated  

{  

    if ([navigationController respondsToSelector:@selector(interactivePopGestureRecognizer)]) {  

        navigationController.interactivePopGestureRecognizer.enabled = YES;  

    }  

}  

除了使用系统默认的动画,还可以使用自定义过渡动画(丰满的文档):

[cpp] view
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- (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;  

    }  

}  

如下这个代理方法是用来提供一个非交互式的过渡动画的:

[cpp] view
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- (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;  

}  

而下面这个代理方法则是提供交互式动画:

[cpp] view
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- (id<UIViewControllerInteractiveTransitioning>)navigationController:(UINavigationController *)navigationController  

                         interactionControllerForAnimationController:(id<UIViewControllerAnimatedTransitioning>)animationController  

{  

    return self.popInteractionController;  

}  

这两个组合起来使用。首先,我们需要有个动画:

[cpp] view
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@interface WQPopAnimator : NSObject <UIViewControllerAnimatedTransitioning>  

  

@end  

[cpp] view
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#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,交互式动画是通过

[cpp] view
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UIPercentDrivenInteractiveTransition  

来维护的,在滑动过程中根据滑动距离来进行更新:

[cpp] view
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} else if (panGesture.state == UIGestureRecognizerStateChanged) {  

        CGPoint translation = [panGesture translationInView:view];  

        CGFloat d = fabs(translation.x / CGRectGetWidth(view.bounds));  

        [self.popInteractionController updateInteractiveTransition:d];  

当手势结束时要做出收尾动作:

[cpp] view
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} else if (panGesture.state == UIGestureRecognizerStateEnded) {  

        if ([panGesture velocityInView:view].x > 0) {  

            [self.popInteractionController finishInteractiveTransition];  

        } else {  

            [self.popInteractionController cancelInteractiveTransition];  

        }  

        self.popInteractionController = nil;  

    }  

同样地,自定义的动画也会有上面提到的导航栏崩溃问题,也可以通过类似的方法来解决:

[cpp] view
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- (void)navigationController:(UINavigationController *)navigationController  

       didShowViewController:(UIViewController *)viewController  

                    animated:(BOOL)animated  

{  

    if (viewController == self.navigationController.pushingViewController) {  

        self.supportPan2Pop = YES;  

        self.navigationController.pushingViewController = nil;  

    }  

补充:位于当前navgationController的第一个([0])viewController时需要设置手势代理,不响应。
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