图片轮播展示完毕的切换卡顿，哪可能逃过产品Dog(就说了能咋地？)的法眼。下面才是入坑的开始：思路是两张一样的图片并排排列，首尾相连，同时左移，设置相同动画时间，X值不断减小，动画结束回调Frame重置方法，递归回调

#import "HCNewLoginViewControllerJJ.h"
#import "MoveAnimationView.h"



@interface HCNewLoginViewControllerJJ ()


@end

@implementation HCNewLoginViewControllerJJ

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
}
- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
    [self startMoveAnimation];
}



- (void)startMoveAnimation {
    UIImage *bgImg = [UIImage imageNamed:@"loginvideoee"];
    CGFloat width = 1.f * bgImg.size.width / bgImg.size.height * kScreenHeight;
    
    UIImageView *bgImgV_1 = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, kScreenWidth, kScreenHeight)];
    bgImgV_1.image = bgImg;
    
    UIImageView *bgImgV_2 = [[UIImageView alloc] initWithFrame:CGRectMake(0, kScreenHeight, kScreenWidth, kScreenHeight)];
    bgImgV_2.image = [UIImage imageNamed:@"loginvideoee"];
    bgImgV_2.contentMode = UIViewContentModeScaleAspectFill;
    bgImgV_1.contentMode = UIViewContentModeScaleAspectFill;
    [self.view addSubview:bgImgV_2];
    [self.view addSubview:bgImgV_1];
    
    CFTimeInterval duration = 12;
    CABasicAnimation *anim1 = [CABasicAnimation animationWithKeyPath:@"transform.translation.y"];
    anim1.toValue = @(-kScreenHeight);
    anim1.duration = duration;
    anim1.repeatCount = HUGE_VALF;
    anim1.removedOnCompletion = NO; //解决页面切换之后，动画久停止的问题，其实是


    [bgImgV_1.layer addAnimation:anim1 forKey:nil];
    
    CABasicAnimation *anim2 = [CABasicAnimation animationWithKeyPath:@"transform.translation.y"];
    anim2.toValue = @(-kScreenHeight);
    anim2.duration = duration;
    anim2.repeatCount = HUGE_VALF;
    anim2.removedOnCompletion = NO;
    [bgImgV_2.layer addAnimation:anim2 forKey:nil];
}


@end

解释：为什么动画结束后返回原状态？
首先我们需要搞明白一点的是，layer动画运行的过程是怎样的？其实在我们给一个视图添加layer动画时，真正移动并不是我们的视图本身，而是 presentation layer 的一个缓存。动画开始时 presentation layer开始移动，原始layer隐藏，动画结束时，presentation layer从屏幕上移除，原始layer显示。这就解释了为什么我们的视图在动画结束后又回到了原来的状态，因为它根本就没动过。

这个同样也可以解释为什么在动画移动过程中，我们为何不能对其进行任何操作。

所以在我们完成layer动画之后，最好将我们的layer属性设置为我们最终状态的属性，然后将presentation layer 移除掉。

至此效果上看来是够优雅了，代码不优雅的地方欢迎指正！