UIScrollView总结

最新推荐文章于 2022-08-25 15:20:34 发布

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最新推荐文章于 2022-08-25 15:20:34 发布

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分类专栏： oc 文章标签： uiscrollview 图片 OC 手势相册

本文链接：https://blog.youkuaiyun.com/a376240118/article/details/48574941

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本文介绍了一个iOS相册应用的实现方法，通过使用嵌套的UIScrollView来实现图片之间的平滑切换及缩放功能。外层scrollView用于控制图片间的切换，内层scrollView负责图片的缩放。

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学习了scrollView一个相册的案例来总结下。
相册起始是一个大的scrollView里面嵌套多个小的scrollView。大的scollView控制图片间的切换，小的scrollView控制图片的缩放。

//创建外面大的scrollView
    UIScrollView *rootAlbum = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0,deviceWidth + 5, deviceHeight)];
    rootAlbum.tag = 10;

    //设置滚动的时候是否按页滚动
    rootAlbum.pagingEnabled = YES;
    rootAlbum.delegate = self;

    //设置scrollView的内容框架坐标
    rootAlbum.contentSize = CGSizeMake((deviceWidth + 5) * 4, deviceHeight);

    //不显示水平滚动条
    rootAlbum.showsHorizontalScrollIndicator = NO;

    //在大的scrollView中添加小的scrollView和图片
    for (int i = 0; i < 4; i ++) {
        PhotoView *myPhoto = [[PhotoView alloc] initWithFrame:CGRectMake(i * (deviceWidth + 5), 0, deviceWidth, deviceHeight)];
        NSString *photoName = [NSString stringWithFormat:@"%d.jpg",i + 1];
        myPhoto.tag = i + 1;
        myPhoto.photo.image = [UIImage imageNamed:photoName];
        [rootAlbum addSubview:myPhoto];
       // NSLog(@"%f",myPhoto.frame.origin.x);
    }
    [self.view addSubview:rootAlbum];
    // Do any additional setup after loading the view, typically from a nib.
}

int current = 1;

//scrollView滚动中调用的方法
- (void)scrollViewDidScroll:(UIScrollView *)scrollView{
    if(scrollView.tag == 10){
        //contentOffset的起点坐标是原始scrollView的左下角那个点
        NSLog(@"%f",scrollView.contentOffset.y);
    }
}

//滚动结束调用的方法
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView{
    int loc = scrollView.contentOffset.x / (deviceWidth + 5) + 1;
    UIScrollView *currentView = (UIScrollView *)[self.view viewWithTag:current];

    //当切换图片时，如果页面有缩放就还原
    if (current != loc && currentView.zoomScale != 1) {
        currentView.zoomScale = 1;
    }
    current = loc;
}

控制图片的scrollView

- (id) initWithFrame:(CGRect)frame{
    self = [super initWithFrame:frame];
    if (self) {
        self.delegate = self;
        _photo = [[UIImageView alloc] initWithFrame:self.bounds];
        self.showsHorizontalScrollIndicator = NO;

        //设置最大缩放
        self.maximumZoomScale = 2.5;
        //设置最小缩放
        self.minimumZoomScale = 0.5;

        [self addSubview:_photo];

        //创建双击事件，当双击图片时放大双击的位置
        UITapGestureRecognizer *doubleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(doubleTapEvent :)];
        doubleTap.numberOfTapsRequired = 2;
        [self addGestureRecognizer:doubleTap];
    }
    return self;
}

- (void) doubleTapEvent : (UITapGestureRecognizer *) doubleTap{

    //如果当前页面没有缩放双击则放大双击部位，如果有缩放则还原
    if(self.zoomScale == 1 ){
        [UIView animateWithDuration:0.5 animations:^{
            CGPoint point = [doubleTap locationInView:self];

            //以所点击位置为中心的长80宽80的矩形填充当前的scrollView
            [self zoomToRect:CGRectMake(point.x - 40, point.y - 40, 80, 80) animated:YES];
        }];
    }else{
        [UIView animateWithDuration:0.5 animations:^{
            self.zoomScale = 1;
        }];
    }
}

//让代理对象实现下面的方法，返回需要缩放的视图控件
- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView{
    return _photo;
}