浇花动画

效果图：

切图：

RootViewController.m

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.

    //初始化背景图
    [self initBackGroundView];

}
#pragma -mark -functions
//背景图
-(void)initBackGroundView
{
    //人
    UIImageView *loadPeopleView = [[UIImageView alloc] initWithFrame:CGRectMake(130, 100, 156, 172)];
    loadPeopleView.tag = 101;
    loadPeopleView.alpha = 1.0f;
    loadPeopleView.backgroundColor=[UIColor clearColor];
    [loadPeopleView setImage:[UIImage imageNamed:@"problem_load.png"]];

    //花
    UIImageView *loadFlowerView = [[UIImageView alloc] initWithFrame:CGRectMake(70, 200, 62, 75)];
    loadFlowerView.tag = 102;
    loadFlowerView.alpha = 1.0f;
    [loadFlowerView setImage:[UIImage imageNamed:@"problem_load1.png"]];

    [self.view addSubview:loadPeopleView];
    [self.view addSubview:loadFlowerView];

    timer = [NSTimer scheduledTimerWithTimeInterval:0.5 target:self selector:@selector(animation:) userInfo:nil repeats:YES];
}
//动画
- (void)animation:(NSTimer *)timer
{
    NSLog(@"-i-%i--",i);
    UIImageView *imageView = (UIImageView *)[self.view viewWithTag:102];
    i++;
    if (i%3 == 0) {
        [imageView setImage:[UIImage imageNamed:@"problem_load1.png"]];
    }else if (i%3 == 1){
        [imageView setImage:[UIImage imageNamed:@"problem_load2.png"]];
    }else{
        [imageView setImage:[UIImage imageNamed:@"problem_load3.png"]];
    }
}