項目需求：圖片瀏覽器（可以左右切換，需要支持手勢縮放的功能）https://github.com/Shannoon/XLPhotoBrowser.git ，網上搜羅了很多框架不合適。感謝魏希的分享http://www.itdecent.cn/p/03c81ee888f4 ?，F(xiàn)在貼出來以后備用

效果圖如下：

photoBrowser.gif

Github：https://github.com/briceZhao/ZoomingImageBrowser

代碼

• AZCollectionViewCell.m中

- (void)configSubViews{
    UIScrollView *scrollView = [[UIScrollView alloc] initWithFrame:self.bounds];
    scrollView.delegate = self;
    scrollView.maximumZoomScale = 3.0;//最大縮放倍數(shù)
    scrollView.minimumZoomScale = 1.0;//最小縮放倍數(shù)
    scrollView.showsVerticalScrollIndicator = NO;
    scrollView.showsHorizontalScrollIndicator = NO;
    scrollView.backgroundColor = [UIColor blackColor];
    [self addSubview:scrollView];
    self.scrollView = scrollView;
    
    UIImageView *imageView = [[UIImageView alloc] init];
    imageView.userInteractionEnabled = YES;//在UIImageView上加手勢識別，打開用戶交互
    UITapGestureRecognizer *doubleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleDoubleTap:)];
    [doubleTap setNumberOfTapsRequired:2];
    [imageView addGestureRecognizer:doubleTap];//添加雙擊手勢
    [scrollView addSubview:imageView];
    self.imageView = imageView;
}

• 屬性的setImage方法中重新設置UIImageView的圖片和尺寸以及ScrollView的縮放比例

- (void)setImage:(UIImage *)image{
    _image = image;
    self.imageView.image = image;
    CGFloat width = image.size.width;
    CGFloat height = image.size.height;
    CGFloat maxHeight = self.scrollView.bounds.size.height;
    CGFloat maxWidth = self.scrollView.bounds.size.width;
    //如果圖片尺寸大于view尺寸，按比例縮放
    if(width > maxWidth || height > width){
        CGFloat ratio = height / width;
        CGFloat maxRatio = maxHeight / maxWidth;
        if(ratio < maxRatio){
            width = maxWidth;
            height = width*ratio;
        }else{
            height = maxHeight;
            width = height / ratio;
        }
    }
    self.scrollView.contentSize = CGSizeMake(width, height);
    [self.scrollView setZoomScale:1.f];
    self.imageView.frame = CGRectMake((maxWidth - width) / 2, (maxHeight - height) / 2, width, height);
    [self.scrollView layoutIfNeeded];
}

• 實現(xiàn)UIScrollViewDelegate，真正的圖片縮放處理

#pragma mark UIScrollViewDelegate
//指定縮放UIScrolleView時，縮放UIImageView來適配
-(UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView{
    return self.imageView;
}

//縮放后讓圖片顯示到屏幕中間
-(void)scrollViewDidZoom:(UIScrollView *)scrollView{
    CGSize originalSize = _scrollView.bounds.size;
    CGSize contentSize = _scrollView.contentSize;
    CGFloat offsetX = originalSize.width > contentSize.width ? (originalSize.width - contentSize.width) / 2 : 0;
    CGFloat offsetY = originalSize.height > contentSize.height ? (originalSize.height - contentSize.height) / 2 : 0;
    self.imageView.center = CGPointMake(contentSize.width / 2 + offsetX, contentSize.height / 2 + offsetY);
}

- (void)handleDoubleTap:(UITapGestureRecognizer *)recongnizer
{
    UIGestureRecognizerState state = recongnizer.state;
    switch (state) {
        case UIGestureRecognizerStateBegan:
            break;
        case UIGestureRecognizerStateChanged:
            break;
        case UIGestureRecognizerStateCancelled:
        case UIGestureRecognizerStateEnded:
        {
            //以點擊點為中心，放大圖片
            CGPoint touchPoint = [recongnizer locationInView:recongnizer.view];
            BOOL zoomOut = self.scrollView.zoomScale == self.scrollView.minimumZoomScale;
            CGFloat scale = zoomOut?self.scrollView.maximumZoomScale:self.scrollView.minimumZoomScale;
            [UIView animateWithDuration:0.3 animations:^{
                self.scrollView.zoomScale = scale;
                if(zoomOut){
                    CGFloat x = touchPoint.x*scale - self.scrollView.bounds.size.width / 2;
                    CGFloat maxX = self.scrollView.contentSize.width-self.scrollView.bounds.size.width;
                    CGFloat minX = 0;
                    x = x > maxX ? maxX : x;
                    x = x < minX ? minX : x;
                    
                    CGFloat y = touchPoint.y * scale-self.scrollView.bounds.size.height / 2;
                    CGFloat maxY = self.scrollView.contentSize.height-self.scrollView.bounds.size.height;
                    CGFloat minY = 0;
                    y = y > maxY ? maxY : y;
                    y = y < minY ? minY : y;
                    self.scrollView.contentOffset = CGPointMake(x, y);
                }
            }];
            
        }
            break;
        default:break;
    }
}

以上的代碼就能實現(xiàn)圖片輪播或者圖片瀏覽器/照片查看器等等的瀏覽圖片類，手勢縮放的效果了，以上代碼參考了魏希的分享http://www.itdecent.cn/p/03c81ee888f4 ， 感謝原作者。貼出來希望更多的人能用上這個方法