iOS图片预览、放大缩小

• 思路

  图片预览，优先考虑基础控件UIImageView、UIButton

  图片预览中可能需设置不同的mode，优先考虑UIImageView

  typedef NS_ENUM(NSInteger, UIViewContentMode) {
      UIViewContentModeScaleToFill,
      UIViewContentModeScaleAspectFit,      
      UIViewContentModeScaleAspectFill,     
      UIViewContentModeRedraw,             
      UIViewContentModeCenter,              
      UIViewContentModeTop,
      UIViewContentModeBottom,
      UIViewContentModeLeft,
      UIViewContentModeRight,
      UIViewContentModeTopLeft,
      UIViewContentModeTopRight,
      UIViewContentModeBottomLeft,
      UIViewContentModeBottomRight,
  }
  
  

  图片放大、缩小的思路：1. 手势+frame 2.scrollview的zoomScale

  很愉快的决定选择2，不要问为什么，因为我懒，能用系统提供的，坚决不折腾

• 上菜

  • 设置页面属性

  @property (nonatomic, strong) UIScrollView *mScroll;
  @property (nonatomic, strong) UIImageView *imgInfo;
  
  

  • 界面初始化

  self.mScroll = [[UIScrollView alloc] initWithFrame:CGRectZero];
  self.mScroll.backgroundColor = [UIColor colorWithHexs:0x3f3f3f];
  self.mScroll.maximumZoomScale = 3.0;
  self.mScroll.minimumZoomScale = 1;
  self.mScroll.delegate = self;
  self.mScroll.showsVerticalScrollIndicator = NO;
  self.mScroll.showsHorizontalScrollIndicator = NO;
  [self.view addSubview:self.mScroll];
  [self.mScroll mas_makeConstraints:^(MASConstraintMaker *make) {
      make.edges.equalTo(self.preView);
  }];
  
  self.imgInfo = [[UIImageView alloc] initWithFrame:CGRectZero];
  self.imgInfo.clipsToBounds = YES;
  [self.imgInfo setUserInteractionEnabled:YES];
  self.imgInfo.backgroundColor = [UIColor colorWithHexs:0x3f3f3f];
  [self.mScroll addSubview:self.imgInfo];
  [self.imgInfo mas_makeConstraints:^(MASConstraintMaker *make) {
      make.edges.equalTo(self.mScroll);
      make.width.equalTo(self.mScroll);
  }];
  
  

  其中maximumZoomScale与minimumZoomScale表示可缩放程度

  • 顺带加个双击手势，比如双击可放大，再放大，再缩小

  UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tapHandlerTwice)];
  tap.numberOfTapsRequired = 2;
  [self.imgInfo addGestureRecognizer:tap];
  
  

  • double click直接控制缩放

  - (void)tapHandlerTwice {
    if (self.mScroll.zoomScale < 2) {
        [self.mScroll setZoomScale:2];
    } else if (self.mScroll.zoomScale < 3) {
        [self.mScroll setZoomScale:3];
    } else {
        [self.mScroll setZoomScale:1];
    }
  }
  
  

  • UIScrollViewDelegate设置scrollview的Zooming View

  #pragma mark - UIScrollViewDelegate
  - (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView {
      return self.imgInfo;
  }
  
  

这里有一个iOS开发交流群：130595548！如果你也是一个有梦想的iOS开发者，欢迎你的加入！