设置viewcontroller的 self.title 会使tabbaritem的对象改变

美工要求再点击tabbar的时候做一个动画效果，我开始没时间同事帮忙写好了，也就几行代码。
通过找到点击的tabbarbutton 遍历到上面的image的view，然后在上面的layer层做一个动画。

#pragma mark UITabBarDelegate
- (void)tabBar:(UITabBar *)tabBar didSelectItem:(UITabBarItem *)item {
    
    NSInteger index = [tabBar.items indexOfObject:item];
    if (index == self.selectedIndex) {
        return;
    }
    
    //lastAnimationObject 用来记录上次点击的对象
    [self.lastAnimationObject.layer removeAnimationForKey:@"bounce"];
    [self animationWithIndex:index];
}

- (void)animationWithIndex:(NSInteger)index {
    
    NSMutableArray *animationObjects = [NSMutableArray array];
    for (UIView *tabBarButton in self.tabBar.subviews) {
        if ([tabBarButton isKindOfClass:NSClassFromString(@"UITabBarButton")]) {
            for (UIView *tabBarSwappableImageView in tabBarButton.subviews) {
                if ([tabBarSwappableImageView isKindOfClass:NSClassFromString(@"UITabBarSwappableImageView")]) {
                    [animationObjects addObject:tabBarSwappableImageView];
                }
            }
        }
    }
    
    UIView *viewObject = [animationObjects objectAtIndex:index];
    [self bounceAnimationWithAnimationObjects:viewObject index:index];
}

- (void)bounceAnimationWithAnimationObjects:(UIView *)viewObject index:(NSInteger)index {
    
    CAKeyframeAnimation *keyFrameAnimation = [CAKeyframeAnimation animationWithKeyPath:@"transform.scale"];
    keyFrameAnimation.values = @[@1.0 ,@1.4, @0.9, @1.15, @0.95, @1.02, @1.0];
    keyFrameAnimation.duration = 0.5;
    keyFrameAnimation.calculationMode = kCAAnimationCubic;
    [viewObject.layer addAnimation:keyFrameAnimation forKey:@"bounce"];
    self.lastAnimationObject = viewObject;
}

开始运行的时候没问题，后来测试反馈点击第三个的时候第四个做动画，第四个的时候第三个做动画。通过打印便利对象发现是因为点击点三个的时候第三个button的对象发生了改变重新创建了一次，所以在数组中三四的对象的位置是相反的。