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iOS图片预览、放大缩小

2021-02-17 16:34 2316 查看
  • 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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