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

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转载自blog.51cto.com/15070994/2630438

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