@interface MJViewController ()
{
    //在私有擴展中創(chuàng)建一個屬性
    UIScrollView *_scrollView;
}
@end

@implementation MJViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
   
    // 1.創(chuàng)建UIScrollView
    UIScrollView *scrollView = [[UIScrollView alloc] init];
    scrollView.frame = CGRectMake(0, 0, 250, 250); // frame中的size指UIScrollView的可視范圍
    scrollView.backgroundColor = [UIColor grayColor];
    [self.view addSubview:scrollView];
   
    // 2.創(chuàng)建UIImageView（圖片）
    UIImageView *imageView = [[UIImageView alloc] init];
    imageView.image = [UIImage imageNamed:@"big.jpg"];
    CGFloat imgW = imageView.image.size.width; // 圖片的寬度
    CGFloat imgH = imageView.image.size.height; // 圖片的高度
    imageView.frame = CGRectMake(0, 0, imgW, imgH);
    [scrollView addSubview:imageView];
   
    // 3.設(shè)置scrollView的屬性
   
    // 設(shè)置UIScrollView的滾動范圍（內(nèi)容大小）
    scrollView.contentSize = imageView.image.size;
   
    // 隱藏水平滾動條
    scrollView.showsHorizontalScrollIndicator = NO;
    scrollView.showsVerticalScrollIndicator = NO;
   
    // 用來記錄scrollview滾動的位置
//    scrollView.contentOffset = ;
   
    // 去掉彈簧效果
//    scrollView.bounces = NO;
   
    // 增加額外的滾動區(qū)域（逆時針，上、左、下、右）
    // top  left  bottom  right
    scrollView.contentInset = UIEdgeInsetsMake(20, 20, 20, 20);
   
    _scrollView = scrollView;
}

- (IBAction)down:(UIButton *)sender {
    [UIView animateWithDuration:1.0 animations:^{
        //三個步驟
        CGPoint offset = _scrollView.contentOffset;
        offset.y += 150;
        _scrollView.contentOffset = offset;
       
        //_scrollView.contentOffset = CGPointMake(0, 0);
    }];
}
@end

@interface YYViewController () <UIScrollViewDelegate>
{
    UIScrollView *_scrollview;
    UIImageView *_imageview;
}
@end

- (void)viewDidLoad
{
    [super viewDidLoad];
   
    //1添加 UIScrollView
    //設(shè)置 UIScrollView的位置與屏幕大小相同
    _scrollview=[[UIScrollView alloc]initWithFrame:self.view.bounds];
    [self.view addSubview:_scrollview];
   
    //2添加圖片
    //有兩種方式
    //(1)一般方式
//    UIImageView  *imageview=[[UIImageView alloc]init];
//    UIImage *image=[UIImage imageNamed:@"minion"];
//    imageview.image=image;
//    imageview.frame=CGRectMake(0, 0, image.size.width, image.size.height);
   
    //(2)使用構(gòu)造方法
    UIImage *image=[UIImage imageNamed:@"minion"];
    _imageview=[[UIImageView alloc]initWithImage:image];
    //調(diào)用initWithImage:方法，它創(chuàng)建出來的imageview的寬高和圖片的寬高一樣
    [_scrollview addSubview:_imageview];
   
    //設(shè)置UIScrollView的滾動范圍和圖片的真實尺寸一致
    _scrollview.contentSize=image.size;
   
   
    //設(shè)置實現(xiàn)縮放
    //設(shè)置代理scrollview的代理對象
    _scrollview.delegate=self;
    //設(shè)置最大伸縮比例
    _scrollview.maximumZoomScale=2.0;
    //設(shè)置最小伸縮比例
    _scrollview.minimumZoomScale=0.5;
   
}

//告訴scrollview要縮放的是哪個子控件
-(UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
    return _imageview;
}

@end

    UIImage *image=[UIImage imageNamed:@"minion"];

    imageview.image=image;

    imageview.frame=CGRectMake(0, 0, image.size.width, image.size.height);

    _imageview=[[UIImageViewalloc]initWithImage:image];