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