首先获取到tabBarItem，然后添加喜欢的动画，直接附代码

@interface MNTabBarController () 

//记录上一次点击tabbar，使用时，记得先在init或viewDidLoad里 初始化 = 0
@property (nonatomic, assign) NSInteger indexFlag;

@end

@implementation MNTabBarController

#pragma mark - UITabBarDelegate

- (void)tabBar:(UITabBar *)tabBar didSelectItem:(UITabBarItem *)item
{
    /** 给 tabBarButton 加动画 */
    NSInteger index = [self.tabBar.items indexOfObject:item];
    if (index != self.indexFlag) {
        //执行动画
        NSMutableArray *arry = [NSMutableArray array];
        for (UIView *btn in self.tabBar.subviews) {
            if ([btn isKindOfClass:NSClassFromString(@"UITabBarButton")]) {
                [arry addObject:btn];
            }
        }
        //添加动画
        [self addUpTranslationAnimtaionWithArr:arry index:index];
        
        self.indexFlag = index;
    }
}

#pragma mark - More Animation

/// 先放大，再缩小
- (void)addScaleAnimtaionWithArr:(NSMutableArray *)arry index:(NSInteger)index
{
    //放大效果，并回到原位
    CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"transform.scale"];
    //速度控制函数，控制动画运行的节奏
    animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
    animation.duration = 0.2;       //执行时间
    animation.repeatCount = 1;      //执行次数
    animation.autoreverses = YES;    //完成动画后会回到执行动画之前的状态
    animation.fromValue = [NSNumber numberWithFloat:0.7];   //初始伸缩倍数
    animation.toValue = [NSNumber numberWithFloat:1.3];     //结束伸缩倍数
    [[arry[index] layer] addAnimation:animation forKey:nil];
}

/// Z轴旋转
- (void)addRotationAnimtaionWithArr:(NSMutableArray *)arry index:(NSInteger)index
{
    //z轴旋转180度
    CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"transform.rotation.z"];
    //速度控制函数，控制动画运行的节奏
    animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
    animation.duration = 0.2;       //执行时间
    animation.repeatCount = 1;      //执行次数
    animation.removedOnCompletion = YES;
    animation.fromValue = [NSNumber numberWithFloat:0];   //初始伸缩倍数
    animation.toValue = [NSNumber numberWithFloat:M_PI];     //结束伸缩倍数
    [[arry[index] layer] addAnimation:animation forKey:nil];
}

/// 向上移动
- (void)addUpTranslationAnimtaionWithArr:(NSMutableArray *)arry index:(NSInteger)index
{
    //向上移动
    CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"transform.translation.y"];
    //速度控制函数，控制动画运行的节奏
    animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
    animation.duration = 0.2;       //执行时间
    animation.repeatCount = 1;      //执行次数
    animation.removedOnCompletion = YES;
    animation.fromValue = [NSNumber numberWithFloat:0];   //初始伸缩倍数
    animation.toValue = [NSNumber numberWithFloat:-10];     //结束伸缩倍数
    [[arry[index] layer] addAnimation:animation forKey:nil];
}


/// 放大并保持
- (void)addscaleAndKeepAnimtaionWithArr:(NSMutableArray *)arry index:(NSInteger)index
{
    //放大效果
    CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"transform.scale"];
    //速度控制函数，控制动画运行的节奏
    animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
    animation.duration = 0.2;       //执行时间
    animation.repeatCount = 1;      //执行次数
    animation.removedOnCompletion = NO;
    animation.fillMode = kCAFillModeForwards;           //保证动画效果延续
    animation.fromValue = [NSNumber numberWithFloat:1.0];   //初始伸缩倍数
    animation.toValue = [NSNumber numberWithFloat:1.15];     //结束伸缩倍数
    [[arry[index] layer] addAnimation:animation forKey:nil];
    //移除其他tabbar的动画
    for (int i = 0; i<arry.count; i++) {
        if (i != index) {
            [[arry[i] layer] removeAllAnimations];
        }
    }
}

@end