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class="s1">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。
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。