关于tabbarViewController的左右滑动切换

From: https://www.cnblogs.com/zhufengshibei/p/7358159.html

在我们开发的过程中，有时会有左右侧滑tabbarViewController切换控制器的需求，在我自己做项目的时候遇到了此类需求，现在就在此记录一下我当时的做法，废话不多说，直接上代码：

在iOS7.0以前，要实现这样的效果，只有自定义TabBar了，但这很麻烦。而在iOS7.0以后，苹果在UITabBarControllerDelegate中增加了下面两个代理方法：

- (nullable id <UIViewControllerInteractiveTransitioning>)tabBarController:(UITabBarController *)tabBarController  interactionControllerForAnimationController: (id<UIViewControllerAnimatedTransitioning>)animationController； 

- (nullable id <UIViewControllerAnimatedTransitioning>)tabBarController:(UITabBarController *)tabBarController  animationControllerForTransitionFromViewController:(UIViewController *)fromVC toViewController:(UIViewController *)toVC；

自定义的滑动代理，在此实现tabbarViewController的两个新添加的滑动的代理方法

ScrollTabBarDelegate.h


#import <Foundation/Foundation.h>

#import <UIKit/UIKit.h>



@interface ScrollTabBarDelegate : NSObject <UITabBarControllerDelegate>



@property (nonatomic, assign) BOOL interactive; 

@property (nonatomic, strong) UIPercentDrivenInteractiveTransition *interactionController; 



@end

ScrollTabBarDelegate.m

#import "ScrollTabBarDelegate.h" 

#import "ScrollTabBarAnimator.h" 

@interface ScrollTabBarDelegate () 

@property (nonatomic, strong) ScrollTabBarAnimator *tabBarAnimator; 

@end 

@implementation ScrollTabBarDelegate 

- (instancetype)init { 

    if (self = [super init]) { 

        _interactive = NO; 

        _interactionController = [[UIPercentDrivenInteractiveTransition alloc] init]; 

        _tabBarAnimator = [[ScrollTabBarAnimator alloc] init]; 
    } 

    return self; 
} 

- (nullable id <UIViewControllerInteractiveTransitioning>)tabBarController:(UITabBarController *)tabBarController 
                               interactionControllerForAnimationController: (id <UIViewControllerAnimatedTransitioning>)animationController { 

    return self.interactive ? self.interactionController : nil; 
} 

- (nullable id <UIViewControllerAnimatedTransitioning>)tabBarController:(UITabBarController *)tabBarController 
                     animationControllerForTransitionFromViewController:(UIViewController *)fromVC 
                                                       toViewController:(UIViewController *)toVC { 

     

    NSInteger fromIndex = [tabBarController.viewControllers indexOfObject:fromVC]; 

    NSInteger toIndex = [tabBarController.viewControllers indexOfObject:toVC]; 

    self.tabBarAnimator.tabScrollDirection = (toIndex < fromIndex) ? TabLeftDirection: TabRightDirection; 

    return self.tabBarAnimator; 
} 

@end

在自定义一个动画的类，实现滑动切换tabbar时加载动画效果：

ScrollTabBarAnimator.h

#import <Foundation/Foundation.h>

#import <UIKit/UIKit.h>

typedef NS_ENUM(NSInteger,TabOperationDirection) { 
    TabLeftDirection, 
    TabRightDirection 
}; 

@interface ScrollTabBarAnimator : NSObject <UIViewControllerAnimatedTransitioning>

@property (nonatomic, assign) TabOperationDirection tabScrollDirection; 

@end

ScrollTabBarAnimator.m

#import "ScrollTabBarAnimator.h" 

@implementation ScrollTabBarAnimator 

//动画持续时间 
- (NSTimeInterval)transitionDuration:(id <UIViewControllerContextTransitioning>)transitionContext { 

    return 0.3; 
} 

//动画执行效果 
- (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext { 

    // 获取 toView fromView 

    UIViewController* toViewController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey]; 

    UIViewController* fromViewController = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey]; 

    UIView *containerView = [transitionContext containerView]; 

    if (!toViewController || !fromViewController || !containerView) return; 


    // 给 toView fromView 设定相应的值 

    toViewController.view.transform = CGAffineTransformIdentity; 

    fromViewController.view.transform = CGAffineTransformIdentity; 

    CGFloat translation = containerView.frame.size.width; 

    switch (self.tabScrollDirection) { 

        case TabLeftDirection: 

            translation = translation; 

            break; 

        case TabRightDirection: 

            translation = -translation; 

            break; 

        default: 

            break; 

    } 


    [containerView addSubview:toViewController.view]; 

    toViewController.view.transform = CGAffineTransformMakeTranslation(-translation, 0); 

    // 真正的变化 

    [UIView animateWithDuration:[self transitionDuration:transitionContext] animations:^{ 

        fromViewController.view.transform = CGAffineTransformMakeTranslation(translation, 0); 

        toViewController.view.transform = CGAffineTransformIdentity; 

    } completion:^(BOOL finished) { 

        fromViewController.view.transform = CGAffineTransformIdentity; 

        toViewController.view.transform = CGAffineTransformIdentity; 

        [transitionContext completeTransition:![transitionContext transitionWasCancelled]]; 

    }]; 
} 

@end

在 TabBarController.m 中实现的方法，导入 ScrollTabBarDelegate 的头文件后，声明两个对象

@property (nonatomic, assign) NSInteger subViewControllerCount; 

@property (nonatomic, strong) ScrollTabBarDelegate *tabBarDelegate; 

- (void)viewDidLoad { 

    [super viewDidLoad]; 

    #pragma mark   tabbar滑动切换手势 

    // 正确的给予 count 

   self.subViewControllerCount = self.viewControllers ? self.viewControllers.count : 0; 

   // 设置 tabbarViewController 的代理为 ScrollTabBarDelegate ，并给 tabbarViewController 的view添加滑动手势 

    // 代理 

    self.tabBarDelegate = [[ScrollTabBarDelegate alloc] init]; 

    self.delegate = self.tabBarDelegate; 

    // 增加滑动手势 

    self.panGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(panHandle:)]; 

    [self.view addGestureRecognizer:self.panGesture]; 
} 

//实现滑动手势，切换tabbarViewController的item到不同的控制器 
- (void)panHandle:(UIPanGestureRecognizer *)panGesture { 

    // 获取滑动点 

    CGFloat translationX = [panGesture translationInView:self.view].x; 

    CGFloat progress = fabs(translationX)/self.view.frame.size.width; 

    switch (panGesture.state) { 
        case UIGestureRecognizerStateBegan: 
        { 
            self.tabBarDelegate.interactive = YES; 

            CGFloat velocityX = [panGesture velocityInView:self.view].x; 

            if (velocityX < 0) { 

                if (self.selectedIndex < self.subViewControllerCount - 1) { 

                    self.selectedIndex += 1; 

                } 

            }  else { 

                if (self.selectedIndex > 0) { 
                    self.selectedIndex -= 1; 
                } 
            } 
        } 
            break; 
        case UIGestureRecognizerStateChanged: 
        { 
            [self.tabBarDelegate.interactionController updateInteractiveTransition:progress]; 
        } 
            break; 
        case UIGestureRecognizerStateEnded: 
        case UIGestureRecognizerStateFailed: 
        case UIGestureRecognizerStateCancelled: 
        { 
            if (progress > 0.3) { 

                self.tabBarDelegate.interactionController.completionSpeed = 0.99; 

                [self.tabBarDelegate.interactionController finishInteractiveTransition]; 

            } else { 

                //转场取消后，UITabBarController 自动恢复了 selectedIndex 的值，不需要我们手动恢复。 

                self.tabBarDelegate.interactionController.completionSpeed = 0.99; 

                [self.tabBarDelegate.interactionController cancelInteractiveTransition]; 
            } 

            self.tabBarDelegate.interactive = NO; 
        } 
            break; 
        default: 
            break; 
    } 
}

这样实现以后，会出现一个问题，就是当跳转到子控制器的时候，子控制器也可以滑动，这就不对了，于是果断的开始查找原因，发现所有的控制器的

rootViewController 都是 tabbarViewController，所以需要在跳转的时候吧 tabbarViewController 的view的滑动手势给移除掉，当返回来的时候再给加上去，于是把 UIPanGestureRecognizer 的对象在tabbarViewController.h 中搞成一个全局对象

@property (nonatomic, strong) UIPanGestureRecognizer *panGesture;

在自定义的 UINavigationController 中，重写 pushViewController 方法，在此方法中移除tabbarViewController 的view的滑动手势，代码如下：

- (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated { 

    if (self.viewControllers.count > 0) { 

        viewController.hidesBottomBarWhenPushed = YES; 

        // 跳转后移除滑动手势 
        [[UIApplication sharedApplication].delegate.window.rootViewController.view removeGestureRecognizer:viewController.cyl_tabBarController.panGesture]; 

 　　    //注册一个通知，通知在第一层的控制器吧tabbarViewController 的view的滑动手势给添加上去 
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(scrollNextViewController) name:@"SCROLLTABBARCONTROLLER" object:nil]； 
    } 

    [super pushViewController:viewController animated:animated]; 
}

当返回到第一层的控制器的时候，在返回按钮点击的时候发布一个通知，通知在第一层的控制器吧tabbarViewController 的view的滑动手势给添加上去

-(void)scrollNextViewController { 

    if (self.childViewControllers.count == 1 && [(AppDelegate *)[UIApplication sharedApplication].delegate isBackBtn] == YES) { 

        // 返回后重新添加滑动手势 

        [[UIApplication sharedApplication].delegate.window.rootViewController.view addGestureRecognizer:[UIApplication sharedApplication].delegate.window.rootViewController.cyl_tabBarController.panGesture]; 
    } 
}

结束后别忘了移除通知

- (void)dealloc { 

    [[NSNotificationCenter defaultCenter] removeObserver:self]; 
}

到此处，关于tabbarViewController的左右滑动切换的问题算是解决了。