放大到 UIImageView 的问题

Question

我正在关注 Apple 的 ScrollSuite 示例，但是捏缩放不起作用。我不知道怎么了：

// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad {
    [super viewDidLoad];

    // set up main scroll view
    imageScrollView = [[UIScrollView alloc] initWithFrame:[[self view] bounds]];
    [imageScrollView setBackgroundColor:[UIColor blackColor]];
    [imageScrollView setDelegate:self];
    [imageScrollView setBouncesZoom:YES];
    [[self view] addSubview:imageScrollView];

    // add touch-sensitive image view to the scroll view
    UIImageView *imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"default.png"]];
    [imageView setTag:ZOOM_VIEW_TAG];
    [imageView setUserInteractionEnabled:YES];
    [imageScrollView setContentSize:[imageView frame].size];
    [imageScrollView addSubview:imageView];
    [imageView release];

    // calculate minimum scale to perfectly fit image width, and begin at that scale
    float minimumScale = [imageScrollView frame].size.width  / [imageView frame].size.width;
    [imageScrollView setMinimumZoomScale:minimumScale];
    [imageScrollView setZoomScale:minimumScale];

    //[self.imageView loadImageFromURL:self.url];
}



// Override to allow orientations other than the default portrait orientation.
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
    // Return YES for supported orientations
    //return (interfaceOrientation == UIInterfaceOrientationPortrait);
    if (enableLandscapeOrientation) {
        [[self navigationController] setNavigationBarHidden:UIInterfaceOrientationIsLandscape(interfaceOrientation) animated:YES];
        return YES;
    }
    else {
        return NO;
    }
}


#pragma mark UIScrollViewDelegate methods

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

/************************************** NOTE **************************************/
/* The following delegate method works around a known bug in zoomToRect:animated: */
/* In the next release after 3.0 this workaround will no longer be necessary      */
/**********************************************************************************/
- (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(float)scale {
    [scrollView setZoomScale:scale+0.01 animated:NO];
    [scrollView setZoomScale:scale animated:NO];
}

#pragma mark Utility methods

- (CGRect)zoomRectForScale:(float)scale withCenter:(CGPoint)center {

    CGRect zoomRect;

    // the zoom rect is in the content view's coordinates. 
    //    At a zoom scale of 1.0, it would be the size of the imageScrollView's bounds.
    //    As the zoom scale decreases, so more content is visible, the size of the rect grows.
    zoomRect.size.height = [imageScrollView frame].size.height / scale;
    zoomRect.size.width  = [imageScrollView frame].size.width  / scale;

    // choose an origin so as to get the right center.
    zoomRect.origin.x    = center.x - (zoomRect.size.width  / 2.0);
    zoomRect.origin.y    = center.y - (zoomRect.size.height / 2.0);

    return zoomRect;
}

Answer 1

仔细检查您的 minimumScale 值。根据该代码并猜测“default.png”是什么，我会说您的 minimumScale 可能是 1.0，这意味着您的滚动视图没有缩放范围。尝试这样做只是为了看看它是否有效：

[imageScrollView setMinimumZoomScale:0.5f];
[imageScrollView setMaximumZoomScale:2.0f];