scrollView浏览图片并缩放

一、应用场景

类似微信发朋友圈添加图片（相册或拍照），点击图片可以浏览，浏览时可对当前图片进行缩放，并且该缩放不影响其他图片正常显示；浏览时可删除图片

二、关键代码

//这里主要的问题是：如果采用cgaffinetransformscale对scrollview进行缩放，则浏览时移到下一张图片也会跟着缩放；如果捏合手势添加到scrollview的imageview中，同样采用cgaffinetransformscale对该图片缩放(pinges.view.transform = cgaffinetransformscale(self.scrollview.transform, newscale, newscale);)并没有效果；

//因此，采用的策略是：在scrollview中嵌套scrollview，然后再嵌套imageview，并且采用zoomtorect缩放，而非cgaffinetransformscale

- (void)culayoutsubviews
{
    bl_loadnavheight;
    self.scrollview = [[uiscrollview alloc] initwithframe:cgrectmake(0, 0, screenwidth_n(), screenheight_n())];
    self.scrollview.backgroundcolor = [uicolor blackcolor];
    [self.view addsubview:self.scrollview];
    
    self.scrollview.delegate = self;
    self.scrollview.pagingenabled = yes;
    self.scrollview.scrollenabled = yes;
    self.scrollview.showshorizontalscrollindicator = no;
    
    [self.imagearr enumerateobjectsusingblock:^(id  _nonnull obj, nsuinteger idx, bool * _nonnull stop) {
        
        uiscrollview *subscrollview = [[uiscrollview alloc] initwithframe:cgrectmake(idx*screenwidth_n(), navviewh, screenwidth_n(), screenheight_n()-navviewh)];
        subscrollview.backgroundcolor = [uicolor blackcolor];
        subscrollview.contentsize = cgsizemake(screenwidth_n(), screenheight_n()-navviewh);
        subscrollview.delegate = self;
        subscrollview.minimumzoomscale = self.minscale;
        subscrollview.maximumzoomscale = self.maxscale;
        [subscrollview setzoomscale:1.0];
        
        uiimage *img = (uiimage *)obj;
        uiimageview *imgview = [[uiimageview alloc] initwithframe:cgrectmake(0, 0, screenwidth_n(), screenheight_n()-navviewh)];
        imgview.userinteractionenabled = yes;
        imgview.contentmode = uiviewcontentmodescaleaspectfit;
        imgview.image = img;
        
        uipinchgesturerecognizer *pin = [[uipinchgesturerecognizer alloc] initwithtarget:self action:@selector(pingesclick:)];
        //捏合手势
        [imgview addgesturerecognizer:pin];
        [subscrollview addsubview:imgview];
        [self.scrollview addsubview:subscrollview];
        
        [self.subscrollviewarr addobject:subscrollview];
        [self.imgviewarr addobject:imgview];
        
    }];
    
    [self adjustscrollviewoffset];
    
    //    uitapgesturerecognizer *tap = [[uitapgesturerecognizer alloc] initwithtarget:self action:@selector(navhidden)];
    //    [self.scrollview addgesturerecognizer:tap];
}

 

- (void)pingesclick:(uipinchgesturerecognizer *)pinges
{
//    switch (pinges.state) {
//        case uigesturerecognizerstatebegan://scale began
//        case uigesturerecognizerstatechanged://scale changed
//        {
//            cgfloat currentscale = [[self.scrollview.layer valueforkeypath:@"transform.scale"] floatvalue];
//            cgfloat newscale = pinges.scale - self.lastscale + 1;
//
//            newscale = min(newscale, self.maxscale / currentscale);
//            newscale = max(newscale, self.minscale / currentscale);
//
//            self.scrollview.transform = cgaffinetransformscale(self.scrollview.transform, newscale, newscale);
//
//            for (int i = 0; i < self.imgviewarr.count; i++) {
//                uiimageview *subimgview = self.imgviewarr[i];
//                nslog(@"subimgview----%d---%@", i, subimgview);
//            }
//
//            self.lastscale = pinges.scale;
//
//
//        }
//            break;
//        case uigesturerecognizerstateended://scale ended
//            self.lastscale = 1;
//            break;
//        default:
//            break;
//    }

    float newscale = [(uiscrollview*)pinges.view.superview zoomscale];
    cgrect zoomrect = [self zoomrectforscale:newscale  inview:(uiscrollview*)pinges.view.superview withcenter:[pinges locationinview:pinges.view]];
    [(uiscrollview*)pinges.view.superview zoomtorect:zoomrect animated:yes];
}

 

//必须返回当前缩放视图——实现代理方法

//放回当前缩放图片
- (uiview *)viewforzoominginscrollview:(uiscrollview *)scrollview
{
    for (uiview *v in scrollview.subviews){
        return v;
    }
    return nil;
}

 

三、效果

 

github