iOS使用UITabBarController时添加视图切换动画

1.创建UITabBarController

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{

//设置UITabBarController为根视图控制器
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    UIViewController *VcA = [[ViewControllerA alloc] initWithNibName:@"VcA" bundle:nil];
    UIViewController *VcB = [[ViewControllerB alloc] initWithNibName:@"VcB" bundle:nil];
    self.tabBarController = [[UITabBarController alloc] init];
    self.tabBarController.viewControllers = @[VcA, VcB];
    self.tabBarController.delegate = self;  // 设置代理
    self.window.rootViewController = self.tabBarController;
    [self.window makeKeyAndVisible];
    return YES;
}

2.在UITabBarController设置代理<UITabBarControllerDelegate>

- (BOOL)tabBarController:(UITabBarController *)tabBarController shouldSelectViewController:(UIViewController *)viewController
{
    //获取选中的VC
    NSUInteger shouldSelectIndex = [tabBarController.viewControllers indexOfObject:viewController];
    if (tabBarController.selectedIndex == shouldSelectIndex) {
        return YES;
    }

    CATransition *animation = [CATransition animation];
    animation.duration = 0.5;
    animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
    animation.type = kCATransitionPush;//设置动画类型（可以试着换下看效果）

//判断要选中的VC在已选中的左边还是右边，进行选择或左或右的push效果
    if (tabBarController.selectedIndex > shouldSelectIndex) {
        animation.subtype = kCATransitionFromLeft;
    } else {
        animation.subtype = kCATransitionFromRight;
    }
    // 下面这句可以换成[tabBarController.view.layer addAnimation:animation forKey:@"reveal"];  但是会导致tabBarController的整个标签栏也跟着一起有动画的效果，这样的效果并不是很好。
    [[[tabBarController valueForKey:@"_viewControllerTransitionView"] layer] addAnimation:animation forKey:@"animation"];

    return YES;
}

参考原文链接：https://www.jianshu.com/p/2525a93c8a68