iOS-UIImageView

CGSize size = [UIScreen mainScreen].bounds.size;
    
    //演示UIImageView的使用, 主要显示图像(png,jpeg)
    //<1>UIImageView 基本使用
    UIImageView *back = [[UIImageView alloc] initWithFrame:self.view.bounds];
    //注意细节:
    //不能显示gif, 使用第三方库显示
    //png可以省略后缀名, jpg一定需要加后缀名
    back.image = [UIImage imageNamed:@"back2.jpg"];
    //  imageNamed图片做缓存, 如果图片太大
    //back.image = [UIImage alloc] initWithData:<#(NSData *)#>;
    NSLog(@"w=%f h=%f",back.image.size.width,back.image.size.height);
    [self.view addSubview:back];
    
    //<2>UIImageView 如何实现动画
    _bird = [[UIImageView alloc] initWithFrame:CGRectMake(100, 100, 120, 96)];
    _bird.image = [UIImage imageNamed:@"DOVE 1.png"];
    [self.view addSubview:_bird];
    
    //设置动画
    //bird.animationDuration
    //bird.animationImages
    //bird.animationRepeatCount
    NSMutableArray *images = [[NSMutableArray alloc] init];
    for (int i=1; i<=18; i++) {
        NSString *name = [NSString stringWithFormat:@"DOVE %d.png",i];
        UIImage *image = [UIImage imageNamed:name];
        [images addObject:image];
    }
    _bird.animationImages = images;
    
    //控制动画速度
    _bird.animationDuration = 18 * 1.0/30;
    
    
    [_bird startAnimating];
    
    //定时器, 很多操作每隔一段时间执行
    //参数1: 每次执行的间隔
    //参数2和3: 指定一个每次执行方法
    //参数4: 传入用户数据
    //参数5: 是否重复
    [NSTimer scheduledTimerWithTimeInterval:0.1 target:self selector:@selector(dealLoop:) userInfo:nil repeats:YES];
    
}
-(void)dealLoop:(NSTimer *)t
{
    double xSpeed = 10;
    CGPoint center = _bird.center;
    center.x += xSpeed;
    if(center.x  > self.view.frame.size.width + _bird.frame.size.width/2)
    {
        center.x = - _bird.frame.size.width / 2;
    }
    _bird.center = center;
    
    //让敌机再次出现
    

}