iOS体验性优化之RTL适配右滑返回的实现

简述

所谓RTL方向布局就是right to left direction。也就是界面中的元素总是按从右往左的方向进行排列布局，大部分国家的书写以及排列习惯都是从左往右，是LTR方向布局，而对于一些阿拉伯国家，文字的书写以及展示的顺序都是从右往左方向的。

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。

总结

频道导航

iOS体验性优化之RTL适配右滑返回的实现

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