#import "ViewController.h"

@interface ViewController ()<UIScrollViewDelegate>

@property (strong, nonatomic) IBOutlet UIScrollView *scrollView;
@property (weak, nonatomic) IBOutlet UIImageView *imageView;

@end

@implementation ViewController

- (void)viewDidLoad
{
  [super viewDidLoad];

  // 设置内容尺寸
  self.scrollView.contentSize = self.imageView.frame.size;

  // 设置
  self.scrollView.delegate = self;

  // 设置最大和最小的缩放比例
  self.scrollView.maximumZoomScale = 2.0;
  self.scrollView.minimumZoomScale = 0.2;

  // 设置边距
  self.scrollView.contentInset = UIEdgeInsetsMake(20, 20, 20, 20);

  // 不显示水平滚动标示
  self.scrollView.showsHorizontalScrollIndicator = NO;

  // 不显示垂直滚动标示
  self.scrollView.showsVerticalScrollIndicator = NO;

  // 偏移位置
  self.scrollView.contentOffset = CGPointMake(0, -100);

  // 取消弹簧效果
  self.scrollView.bounces = NO;

  //设置按钮
  UIButton *btn = [UIButton buttonWithType:UIButtonTypeContactAdd];
  btn.center = self.view.center;

  [self.view addSubview:btn];

  //设置按钮的监听方法
  [btn addTarget:self action:@selector(click) forControlEvents:UIControlEventTouchUpInside];

}

 // 移动大图的偏移位置
- (void)click
{
  //取出offset
  CGPoint offset = self.scrollView.contentOffset;

  offset.x += 20;
  offset.y += 20;

  // 更新contentOffset
  self.scrollView.contentOffset = offset;
}


#pragma mark - UIScrollView的代理方法

// 1> scrollView要知道缩放谁

/**
 * 当用户开始拖拽scrollView时就会调用
 */
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView
{
  NSLog(@"开始拖拽");
}

/**
 * 只要scrollView正在滚动,就会调用
 */
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
  NSLog(@"正在滚动%@", NSStringFromCGPoint(scrollView.contentOffset));
}

/**
 * 当用户使用捏合手势的时候会调用
 *
 * @return 返回的控件就是需要进行缩放的控件
 */
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
  NSLog(@"开始缩放");
  return self.imageView;
}

/**
 * 正在缩放的时候会调用
 */
- (void)scrollViewDidZoom:(UIScrollView *)scrollView
{
  NSLog(@"正在缩放");
}
@end

self.scrollView.contentInset = UIEdgeInsetsMake(20, 20, 20, 20);

 UIButton *btn = [UIButton buttonWithType:UIButtonTypeContactAdd];

- (void)click
{
  CGPoint offset = self.scrollView.contentOffset;

  offset.x += 20;
  offset.y += 20;

  self.scrollView.contentOffset = offset;
}

@property(nonatomic) UIEdgeInsets contentInset;
这个属性能够在UIScrollView的4周增加额外的滚动区域
@property(nonatomic) CGPoint contentOffset; 
这个属性用来表示UIScrollView滚动的位置

@property(nonatomic) CGSize contentSize; 
这个属性用来表示UIScrollView内容的尺寸，滚动范围（能滚多远）

@property(nonatomic) BOOL bounces;
设置UIScrollView是否需要弹簧效果

@property(nonatomic,getter=isScrollEnabled) BOOL scrollEnabled; 
设置UIScrollView是否能滚动

@property(nonatomic) BOOL showsHorizontalScrollIndicator;
是否显示水平滚动条

@property(nonatomic) BOOL showsVerticalScrollIndicator;
是否显示垂直滚动条