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;

• Game Over