iphone - UIScrollview 具有多个图像并捏合缩放

Question

我正在尝试在 iPhone 上复制“照片”应用程序。意思是，具有多个图像的 ScrollView ，并且每个图像都可以捏合来放大/缩小。

Apple ScrollViewSuite 示例代码仅处理 ScrollView 内的 1 个图像。我发现对于多个图像，滚动图像变得不可预测。此外，捏合缩放后 View 会变得不居中。

我在 Stack Overflow 上找到了这个:Zoom UIScrollView with multiple images

但是，我应该在 ScrollView 委托(delegate)函数中编写什么？

Answer 1

这就是我发现的工作原理。支持多幅图像的分页和缩放。享受吧!

#define VIEW_FOR_ZOOM_TAG (1)

@implementation SVViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    UIScrollView *mainScrollView = [[UIScrollView alloc] initWithFrame:self.view.bounds];
    mainScrollView.pagingEnabled = YES;
    mainScrollView.showsHorizontalScrollIndicator = NO;
    mainScrollView.showsVerticalScrollIndicator = NO;

    CGRect innerScrollFrame = mainScrollView.bounds;

    for (NSInteger i = 0; i < 3; i++) {
        UIImageView *imageForZooming = [[UIImageView alloc] initWithImage:[UIImage imageNamed:  
        [NSString stringWithFormat:@"page%d", i + 1]]];
        imageForZooming.tag = VIEW_FOR_ZOOM_TAG;

        UIScrollView *pageScrollView = [[UIScrollView alloc] initWithFrame:innerScrollFrame];
        pageScrollView.minimumZoomScale = 1.0f;
        pageScrollView.maximumZoomScale = 2.0f;
        pageScrollView.zoomScale = 1.0f;
        pageScrollView.contentSize = imageForZooming.bounds.size;
        pageScrollView.delegate = self;
        pageScrollView.showsHorizontalScrollIndicator = NO;
        pageScrollView.showsVerticalScrollIndicator = NO;
        [pageScrollView addSubview:imageForZooming];

        [mainScrollView addSubview:pageScrollView];

        if (i < 2) {
            innerScrollFrame.origin.x += innerScrollFrame.size.width;
        }
    }

    mainScrollView.contentSize = CGSizeMake(innerScrollFrame.origin.x + 
    innerScrollFrame.size.width, mainScrollView.bounds.size.height);

    [self.view addSubview:mainScrollView];
}

- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView {
    return [scrollView viewWithTag:VIEW_FOR_ZOOM_TAG];
}

- (NSUInteger)supportedInterfaceOrientations {
    return UIInterfaceOrientationMaskPortrait;
} 

- (BOOL)shouldAutorotate {
    return NO;
}

@end