iOS圖片預覽、放大縮小

• 思路

  圖片預覽，優先考慮基礎控件UIImageView、UIButton

  圖片預覽中可能需設置不一樣的mode，優先考慮UIImageView

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

  圖片放大、縮小的思路：1. 手勢+frame 2.scrollview的zoomScale

  很愉快的決定選擇2，不要問爲何，由於我懶，能用系統提供的，堅定不折騰

• 上菜

  • 設置頁面屬性

    @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與minimumZoomScale表示可縮放程度
  
  - 順帶加個雙擊手勢，好比雙擊可放大，再放大，再縮小

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

  - double click直接控制縮放

  • (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設置scrollview的Zooming View

    #pragma mark - UIScrollViewDelegate

  • (UIView )viewForZoomingInScrollView:(UIScrollView )scrollView {
    return self.imgInfo;
    }

• Game Over