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[操作系统]App开发流程之右滑返回手势功能续


上一篇记录了利用系统私有变量和方法实现右滑返回手势功能:http://www.cnblogs.com/ALongWay/p/5893515.html

这篇继续记录另一种方案:利用UINavigationController的delegate方法。

核心代理方法有如下两个:

- (nullable id <UIViewControllerInteractiveTransitioning>)navigationController:(UINavigationController *)navigationController             interactionControllerForAnimationController:(id <UIViewControllerAnimatedTransitioning>) animationController NS_AVAILABLE_IOS(7_0);- (nullable id <UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationController                  animationControllerForOperation:(UINavigationControllerOperation)operation                        fromViewController:(UIViewController *)fromVC                         toViewController:(UIViewController *)toVC NS_AVAILABLE_IOS(7_0);

第一个代理方法,要求在视图控制器变换时候,返回一个实现UIViewControllerInteractiveTransitioning协议的对象,该对象用于控制交互进度和状态。

UIKit.h/UIViewControllerTransitioning.h中已经准备好了一个这样的对象,名为UIPercentDrivenInteractiveTransition。

主要关注其如下三个方法:

- (void)updateInteractiveTransition:(CGFloat)percentComplete;//控制交互进度的百分比

- (void)cancelInteractiveTransition;//中途取消交互

- (void)finishInteractiveTransition;//完成交互

可以在一个实现了代理方法的类中,定义一个手势目标方法来调用上述方法,达到控制作为变量的UIPercentDrivenInteractiveTransition对象的目的。

主要代码如下:

- (id<UIViewControllerInteractiveTransitioning>)navigationController:(UINavigationController *)navigationController interactionControllerForAnimationController:(id<UIViewControllerAnimatedTransitioning>)animationController{  if ([animationController isKindOfClass:[PopAnimation class]])    return _interactivePopTransition;    return nil;}- (id<UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationController animationControllerForOperation:(UINavigationControllerOperation)operation fromViewController:(UIViewController *)fromVC toViewController:(UIViewController *)toVC{  if (operation == UINavigationControllerOperationPop)    return _popAnimation;    return nil;}- (void)handlePopGestureOperation:(UIPanGestureRecognizer *)recognizer{  //将手指在屏幕上的移动距离与屏幕宽度比例作为动画的进度  CGPoint translationInScreen = [recognizer translationInView:[UIApplication sharedApplication].keyWindow];  CGFloat progress = translationInScreen.x / [UIScreen mainScreen].bounds.size.width;  progress = MIN(1.0, MAX(0.0, progress));    if (recognizer.state == UIGestureRecognizerStateBegan) {    //新建手势交互对象    _interactivePopTransition = [[UIPercentDrivenInteractiveTransition alloc] init];    //开始执行pop动画    [_naviController popViewControllerAnimated:YES];  }else if (recognizer.state == UIGestureRecognizerStateChanged) {     //更新进度    [_interactivePopTransition updateInteractiveTransition:progress];  }else if (recognizer.state == UIGestureRecognizerStateEnded       || recognizer.state == UIGestureRecognizerStateCancelled) {    //手势结束时如果进度大于一半,那么就完成pop操作,否则取消    if (progress > 0.5) {      [_interactivePopTransition finishInteractiveTransition];    }else {      [_interactivePopTransition cancelInteractiveTransition];    }        //手势交互结束,清理对象    _interactivePopTransition = nil;  }}

 

 

第二个代理方法,要求在操作开始时候,返回一个实现UIViewControllerAnimatedTransitioning协议的对象,该对象实现了动画内容和执行时间。

该协议有三个方法:

// This is used for percent driven interactive transitions, as well as for container controllers that have companion animations that might need to// synchronize with the main animation. - (NSTimeInterval)transitionDuration:(nullable id <UIViewControllerContextTransitioning>)transitionContext;// This method can only be a nop if the transition is interactive and not a percentDriven interactive transition.- (void)animateTransition:(id <UIViewControllerContextTransitioning>)transitionContext;@optional// This is a convenience and if implemented will be invoked by the system when the transition context's completeTransition: method is invoked.- (void)animationEnded:(BOOL) transitionCompleted;

 

第一个方法返回动画时间;第二个方法,可以得到实现了UIViewControllerContextTransitioning协议的对象;第三个方法可选,如果transitionContext对象调用了completeTransition:方法,该代理方法会被调用。

重点是第二个方法的transitionContext对象,其重要的方法如下:

// The view in which the animated transition should take place.- (nullable UIView *)containerView;//动画所在的容器view- (BOOL)transitionWasCancelled;//转换是否取消// This must be called whenever a transition completes (or is cancelled.)// Typically this is called by the object conforming to the// UIViewControllerAnimatedTransitioning protocol that was vended by the transitioning// delegate. For purely interactive transitions it should be called by the// interaction controller. This method effectively updates internal view// controller state at the end of the transition.- (void)completeTransition:(BOOL)didComplete;//完成转换,必须在动画完成时调用// Currently only two keys are defined by the// system - UITransitionContextToViewControllerKey, and// UITransitionContextFromViewControllerKey. // Animators should not directly manipulate a view controller's views and should// use viewForKey: to get views instead.- (nullable __kindof UIViewController *)viewControllerForKey:(NSString *)key;//取得视图控制器// Currently only two keys are defined by the system -// UITransitionContextFromViewKey, and UITransitionContextToViewKey// viewForKey: may return nil which would indicate that the animator should not// manipulate the associated view controller's view.- (nullable __kindof UIView *)viewForKey:(NSString *)key NS_AVAILABLE_IOS(8_0);//取得视图控制器的view,兼容iOS7,可以直接用上面取到的viewController.view

 

创建一个实现UIViewControllerAnimatedTransitioning协议的对象PopAnimation,重要代码如下:

- (NSTimeInterval)transitionDuration:(id <UIViewControllerContextTransitioning>)transitionContext {  return _transitionDuration;}- (void)animateTransition:(id <UIViewControllerContextTransitioning>)transitionContext {  _transitionContext = transitionContext;  //当前控制器  UIViewController *fromViewController = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];    //动画结束显示的控制器  UIViewController *toViewController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];    //执行交互动画的容器view  UIView *containerView = [transitionContext containerView];  [containerView insertSubview:toViewController.view belowSubview:fromViewController.view];    NSTimeInterval duration = [self transitionDuration:transitionContext];    switch (_popAnimationType) {    case PopAnimationTranslation: {      CGFloat containerWidth = containerView.frame.size.width;      toViewController.view.transform = CGAffineTransformMakeTranslation(-containerWidth / 4.0, 0);      [UIView animateWithDuration:duration animations:^{        toViewController.view.transform = CGAffineTransformMakeTranslation(0, 0);        fromViewController.view.transform = CGAffineTransformMakeTranslation(containerWidth, 0);      }completion:^(BOOL finished) {        //动画结束,必须调用此方法        [transitionContext completeTransition:!transitionContext.transitionWasCancelled];      }];      break;    }    case PopAnimationFlip: {      [UIView beginAnimations:@"View Flip" context:nil];      [UIView setAnimationDuration:duration];      [UIView setAnimationDelegate:self];      [UIView setAnimationTransition:UIViewAnimationTransitionFlipFromLeft forView:containerView cache:YES];      [UIView setAnimationDidStopSelector:@selector(animationDidStop:finished:)];      [UIView commitAnimations];      [containerView exchangeSubviewAtIndex:0 withSubviewAtIndex:1];      break;    }    case PopAnimationCube: {      CATransition *transiton = [CATransition animation];      transiton.type = @"cube";      transiton.subtype = @"fromLeft";      transiton.duration = duration;      transiton.removedOnCompletion = NO;      transiton.fillMode = kCAFillModeForwards;      transiton.delegate = self;      [containerView.layer addAnimation:transiton forKey:nil];      [containerView exchangeSubviewAtIndex:0 withSubviewAtIndex:1];      break;    }  }}- (void)animationDidStop:(CATransition *)anim finished:(BOOL)flag {  [_transitionContext completeTransition:!_transitionContext.transitionWasCancelled];}

 

剩下的工作:

在上一篇的基础上,修改UINavigationController的base_pushViewController方法

- (void)base_pushViewController:(UIViewController *)viewController animated:(BOOL)animated{  if (![self.interactivePopGestureRecognizer.view.gestureRecognizers containsObject:self.base_panGestureRecognizer]) {    [self.interactivePopGestureRecognizer.view addGestureRecognizer:self.base_panGestureRecognizer];        self.base_panGestureRecognizer.delegate = [self base_panGestureRecognizerDelegateObject];        self.base_currentDelegateObject = [[NavigationControllerDelegateObject alloc] initWithUINavigationController:self];        [self.base_panGestureRecognizer addTarget:self.base_currentDelegateObject action:@selector(handlePopGestureOperation:)];        self.interactivePopGestureRecognizer.enabled = NO;  }    [self base_setupViewControllerBasedNavigationBarAppearanceIfNeeded:viewController];    if (![self.viewControllers containsObject:viewController]) {    [self base_pushViewController:viewController animated:animated];  }}

可以看到,去除了私有变量和方法的调用,自定义了名为NavigationControllerDelegateObject的对象,其实现了UINavigationControllerDelegate协议,并实现了pan手势的处理方法。在此,我暴露了该属性对象,考虑到以后可能会增加或者修改UINavigationControllerDelegate的实现协议,可以为该对象增加分类来达到目的;还有一个目的,便于修改popAnimation的动画类型和执行时间。

 

总结:

两篇记录,从不同的方向,记录了右滑返回手势功能的实现。利用系统变量和方法,方便快捷;利用协议方法,高度自定义。

但是,利用协议方法,需要处理的方面比较多。虽然上述已经记录了实现核心,示例代码中也有详细代码,但是仍然还有很多方面未考虑。

目前,我发现的一些问题:

1.导航栏交互效果也需要自行实现,暂未实现原生效果

2.导航栏由隐藏到显示的效果,有时会出现异常

3.如果带有bottomBar,效果不理想

 

如果有好的解决办法,希望告知,谢谢。

 

base项目已更新:git@github.com:ALongWay/base.git
项目增加了新的UINavigationController+PopOperation分类,但是未引用到项目中,需要的同学,可先删除PopGesture分类的引用,再添加该分类的应用。