iOS体验性优化---RTL适配右滑返回

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简述

iOS的导航支持左滑手势返回上一个界面，这是果粉普遍喜欢的一个特性，iOS7之后的APP适配大多会保留这一特性，慢慢的大多用户已经有了这种操作习惯，对于iPhone的无虚拟键，这种操作也能增加比较友好的用户体验。

在公司新项目之前，没有考虑过多语言RTL的适配方案，开始做的时候UI方面基本实现用一套布局代码支持RTL的两种布局方向。但是真正拿在手里把玩体验时才真切的感受到没有侧滑返回的RTL有多么的不爽。几经查找并没有找到可参考的合适方案，可能国内做多语言适配的技术圈本身就小，适配RTL的就显得更加的稀有了。

希望能帮助到有需要的人，或者有更好的思路可以联系共同探讨。

思路

查不到可参考的资料，只能自己想一想比较合适的方式，恰好在实现一个首页列表跳转详情页时候，解决特殊的转场动画，突然就有了灵感。可能应该有更好的实现方式，现将我的方式展现给大家。

解决方案

1、关键词： UIPercentDrivenInteractiveTransition finishInteractiveTransition cancelInteractiveTransition
2、关键方法：updateInteractiveTransition:
3、实现方式：暂时以文字代码描述，具体可参考之前共享的RTL解决方案，里面有相关源码，末尾处会贴出路径。

具体实现

1、处理navigation代理

使用runtime方式或者基类方式，viewdidappea每次设置nav的代理为自己，viewdiddisappear清空代理(Yoins新版中使用RTL框架中的分类)

- (void)RTL_viewWillAppear:(BOOL)animated
{
    [self RTL_viewWillAppear:animated];
    self.navigationController.delegate = self;
}
- (void)RTL_viewWillDisappear:(BOOL)animated
{
    [self RTL_viewWillDisappear:animated];
    if (self.navigationController.delegate == self) {
        self.navigationController.delegate = nil;
    }
}

2、右滑手势添加

基类初始化时，RTL环境下添加右滑手势，关闭左滑手势，实现最基本的右滑返回。

Navigation 中实现

- (void)RTL_ViewWillAppear:(BOOL)animate
{
//    self.view.backgroundColor = [UIColor whiteColor];
//    // Do any additional setup after loading the view.
   if (![[RTLManager appearance]RTL]) {
       self.interactivePopGestureRecognizer.delegate = self;
   }
   
   self.interactivePopGestureRecognizer.enabled = ![[RTLManager appearance]RTL];
   
   [self RTL_ViewWillAppear:animate];
}

3、实现手势交互`（重点）`

基类VC中增加一个基础属性，保存临时转场上下文

@property (strong ,nonatomic)UIPercentDrivenInteractiveTransition *transitonContext;

在VC右滑动作触发事件中，处理转场动画进度

- (void)handlePanGesture:(UIScreenEdgePanGestureRecognizer *)pan
{
//    NSLog(@"_____%zd-----%zd",self.navigationController.childViewControllers.count,self.navigationController.viewControllers.count);
//    NSLog(@"----%@",NSStringFromCGPoint([pan translationInView:self.view]));
    
    CGFloat progress = ABS([pan translationInView:self.view].x) / (self.view.bounds.size.width * 1.0);
    progress = MIN(1.0, MAX(0.0, progress));
    
    if (pan.state == UIGestureRecognizerStateBegan) {
        // 创建过渡对象，弹出viewController
        self.transitonContext = [[UIPercentDrivenInteractiveTransition alloc] init];
        [self.navigationController popViewControllerAnimated:YES];
        
    }else if (pan.state == UIGestureRecognizerStateChanged) {
        // 更新 interactive transition 的进度
        [self.transitonContext updateInteractiveTransition:progress];
        
    }else if (pan.state == UIGestureRecognizerStateEnded || pan.state == UIGestureRecognizerStateCancelled) {
        // 完成或者取消过渡
        if (progress > 0.5) {
            [self.transitonContext finishInteractiveTransition];
        }
        else {
            [self.transitonContext cancelInteractiveTransition];
        }
        
        self.transitonContext = nil;
    }
}
- (id<UIViewControllerInteractiveTransitioning>)navigationController:(UINavigationController *)navigationController interactionControllerForAnimationController:(id<UIViewControllerAnimatedTransitioning>)animationController{
    if (self.transitonContext) {
        return self.transitonContext;
    }
    else {
        return nil;
    }
}

最后就是实现自定的各种转场动画了，可以简单模仿系统的滑动切换转场,具体处理在下面VC实现的方法中，返回一个处理转场的实例即可

- (id<UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationController animationControllerForOperation:(UINavigationControllerOperation)operation fromViewController:(UIViewController *)fromVC toViewController:(UIViewController *)toVC

4、贴一个简单的动画处理类

@implementation RTLPushAnimation


- (NSTimeInterval)transitionDuration:(id<UIViewControllerContextTransitioning>)transitionContext
{
    return 0.5;
}
- (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext
{
    UIViewController *fromVC = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
    UIViewController *toVC = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
    
    UIView *container = transitionContext.containerView;
    UIView *tmpV = [fromVC.view snapshotViewAfterScreenUpdates:YES];
    [container addSubview:toVC.view];
    toVC.view.transform = CGAffineTransformMakeTranslation(-toVC.view.bounds.size.width, 0);
    [container addSubview:tmpV];
    [UIView animateWithDuration:[self transitionDuration:transitionContext] animations:^{
        tmpV.transform = CGAffineTransformMakeTranslation(toVC.view.bounds.size.width, 0);
        toVC.view.transform = CGAffineTransformIdentity;
    } completion:^(BOOL finished) {
        [tmpV removeFromSuperview];
        [transitionContext completeTransition:YES];
    }];
    
    
}
@end

@implementation RTLPopAnimation

- (NSTimeInterval)transitionDuration:(id<UIViewControllerContextTransitioning>)transitionContext
{
    return 0.5;
}

- (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext
{
    UIViewController *fromVC = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
    UIViewController *toVC = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
    
    UIView *container = transitionContext.containerView;
    
    UIView *tmpV = [fromVC.view snapshotViewAfterScreenUpdates:YES];
    [container addSubview:toVC.view];
    toVC.view.transform = CGAffineTransformMakeTranslation(toVC.view.bounds.size.width, 0);
    [container addSubview:tmpV];
    [UIView animateWithDuration:[self transitionDuration:transitionContext] animations:^{
        tmpV.transform = CGAffineTransformMakeTranslation(-toVC.view.bounds.size.width, 0);
        toVC.view.transform = CGAffineTransformIdentity;
    } completion:^(BOOL finished) {
        [tmpV removeFromSuperview];
        toVC.view.transform = CGAffineTransformIdentity;
        [transitionContext completeTransition:!transitionContext.transitionWasCancelled];
    }];
}
@end

end

大家或许有更好的处理方案，可以一切探讨下。

新版项目中使用的RTL还在不断地完善中，在公司的公开项目里，有需要可以公开出来。