ios - Objective-C - 无法缩放嵌入到 UIScrollView 中的 UIImageView

Question

我是这里的新人。很高兴认识大家。

我正在尝试实现 Ray Wenderlich 对此处描述的 UIScrollView 的缩放:

http://www.raywenderlich.com/10518/how-to-use-uiscrollview-to-scroll-and-zoom-content

但是好像对我没用。我想做的是:

• 从 nib 创建 UIImageView。
• 将 UIImageView 添加到 UIScrollView。
• 如果应用程序是从 iPad 执行的，则在 View 开始时以 2 的比例从图像中心放大。

这是我的代码:

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.

    //Hide the status bar
    [[UIApplication sharedApplication] setStatusBarHidden:YES];

    //------------------------------
    //Initialize the image view of the home screen
    _mapView = (TM_MapView *)[[[NSBundle mainBundle]loadNibNamed:@"MapView" owner:self options:nil]objectAtIndex:0];

    // set the content size to be the size our our whole frame
    mapScrollView.contentSize = _mapView.imageView.image.size;
    [mapScrollView setScrollEnabled:YES];

    //set the selector for the buttons in the map view
    [self setButtonsSelector];

    // now add our scroll view to the main view
    [mapScrollView addSubview:_mapView];
    //------------------------------

    NSLog(@"_mapView.imageView.frame: %@", NSStringFromCGRect( _mapView.imageView.frame));
    NSLog(@"_mapView.imageView.image.size: %@", NSStringFromCGSize( _mapView.imageView.image.size));
NSLog(@"mapScrollView.contentSize: %@", NSStringFromCGSize( mapScrollView.contentSize));

}

-(void)viewWillAppear:(BOOL)animated
{
    mapScrollView.minimumZoomScale = 1.0f;
    mapScrollView.maximumZoomScale = 2.5f;
    mapScrollView.zoomScale = 1.0f;

    if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad)
    {
        [self zoomOnStart];
    }
}

-(void)zoomOnStart
{
    NSLog(@"Zooming on start");
    CGPoint zoomPoint = CGPointMake(512.0f, 384.0f);

    CGFloat newZoomScale = 2.0f;

    CGSize scrollViewSize = self.mapScrollView.bounds.size;

    CGFloat w = scrollViewSize.width / newZoomScale;
    CGFloat h = scrollViewSize.height / newZoomScale;
    CGFloat x = zoomPoint.x - (w/2.0f);
    CGFloat y = zoomPoint.y - (h/2.0f);

    CGRect rectToZoomTo = CGRectMake(x, y, w, h);
    //CGRect rectToZoomTo = CGRectMake(300, 300, 200, 100);

    NSLog(@"rectToZoomTo: %@", NSStringFromCGRect(rectToZoomTo));

    [self.mapScrollView zoomToRect:rectToZoomTo animated:YES];

}

#pragma mark - Delegates
-(UIView*)viewForZoomingInScrollView:(UIScrollView*)scrollView
{
    NSLog(@"Scroll View viewForZoomingInScrollView");
    return _mapView;
}

-(void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(CGFloat)scale
{
    NSLog(@"Scroll View End Zooming!");
}

-(void)scrollViewDidZoom:(UIScrollView *)scrollView
{
    NSLog(@"Scroll View Zoom changed to: %f",  scrollView.zoomScale);
}

如您所见，我记录了一些帧和委托(delegate)以查看缩放的输入并查看我们是否正在缩放。这是控制台日志:

2014-10-09 17:24:18.507 TrueMuzeiOS[13268:60b] _mapView.imageView.frame: {{0, 0}, {1024, 768}}
2014-10-09 17:24:18.511 TrueMuzeiOS[13268:60b] _mapView.imageView.image.size: {1024, 768}
2014-10-09 17:24:18.513 TrueMuzeiOS[13268:60b] mapScrollView.contentSize: {1024, 768}
2014-10-09 17:24:18.519 TrueMuzeiOS[13268:60b] Zooming on start
2014-10-09 17:24:18.521 TrueMuzeiOS[13268:60b] rectToZoomTo: {{320, 128}, {384, 512}}

如您所见，viewForZoomingInScrollView:、scrollViewDidEndZooming:withView:atScale: 和 scrollViewDidZoom: 中的日志未被调用，这意味着我们根本没有缩放(CMIIW)。我已经添加了 UIScrollViewDelegate，因此它应该可以正常工作。

那么，你们能帮帮我吗？恕我直言，我已经正确地执行了这些步骤。所以我现在迷路了。非常感谢。

Answer 1

是否设置了 UIScrollView 的 delegate 属性？

虽然您可以在 Interface Builder 上完成，但我在您发布的代码中没有看到这一点。

如果是这种情况，只需这样就可以调用您的方法:

mapScrollView.delegate = self;

查看有关委托(delegate)属性部分的 UIScrollView 文档以了解更多信息。

https://developer.apple.com/library/ios/documentation/uikit/reference/uiscrollview_class/index.html#//apple_ref/occ/instp/UIScrollView/delegate