第三十八篇、给UITabBar按钮的动画效果

 在很多情况下，我们也时常有这样的需求，就是在UITabBar切换的时候，添加一些动画效果

1.在UITabBar触发点击方法的时候捕获当前点击的item

2.使用coreAnimation设置动画效果

- (void)tabBar:(UITabBar *)tabBar didSelectItem:(UITabBarItem *)item {

    NSInteger index = [self.tabBar.items indexOfObject:item];

    if (self.indexFlag != index) {
        [self animationWithIndex:index];
    }

}
// 动画
- (void)animationWithIndex:(NSInteger) index {
    NSMutableArray * tabbarbuttonArray = [NSMutableArray array];
    for (UIView *tabBarButton in self.tabBar.subviews) {
        if ([tabBarButton isKindOfClass:NSClassFromString(@"UITabBarButton")]) {
            [tabbarbuttonArray addObject:tabBarButton];
        }
    }
    CABasicAnimation*pulse = [CABasicAnimation animationWithKeyPath:@"transform.scale"];
    pulse.timingFunction= [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
    pulse.duration = 0.08;
    pulse.repeatCount= 1;
    pulse.autoreverses= YES;
    pulse.fromValue= [NSNumber numberWithFloat:0.7];
    pulse.toValue= [NSNumber numberWithFloat:1.3];
    [[tabbarbuttonArray[index] layer]
     addAnimation:pulse forKey:nil];

    self.indexFlag = index;

}