• Train of thought

    Image preview, give priority to basic controls UIImageView, UIButton

    Image preview may require different modes, with UIImageView being preferred

    typedef NS_ENUM(NSInteger, UIViewContentMode) {
    UIViewContentModeScaleToFill,
    UIViewContentModeScaleAspectFit,      
    UIViewContentModeScaleAspectFill,     
    UIViewContentModeRedraw,             
    UIViewContentModeCenter,              
    UIViewContentModeTop,
    UIViewContentModeBottom,
    UIViewContentModeLeft,
    UIViewContentModeRight,
    UIViewContentModeTopLeft,
    UIViewContentModeTopRight,
    UIViewContentModeBottomLeft,
    UIViewContentModeBottomRight,
}
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    1. Gesture +frame 2. Scrollview zoomScale

    Very pleasant decision choice 2, don’t ask why, because I am lazy, can use the system to provide, do not bother

  • serving

    • Setting page Properties
    @property (nonatomic, strong) UIScrollView *mScroll;
@property (nonatomic, strong) UIImageView *imgInfo;
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    • Interface initialization
    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); }];Copy the code

    MaximumZoomScale and minimumZoomScale represent the scaling degree

    • Add a double – click gesture, such as double – click to zoom in, zoom in, zoom out
    UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tapHandlerTwice)];
tap.numberOfTapsRequired = 2;
[self.imgInfo addGestureRecognizer:tap];
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    • Double click controls scaling directly
    - (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]; }}Copy the code
    • UIScrollViewDelegate sets the Zooming View of the ScrollView
    #pragma mark - UIScrollViewDelegate
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView {
    return self.imgInfo;
}
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  • Game Over