* Terminating app due to uncaught exception 'CALayerInvalidGeometry',reason: 'CALayer position contains NaN: [nan nan]'
以下是相关的堆栈跟踪:
Thread 1, Queue : (null)
#0 0x01dd5caa in objc_exception_throw ()
#1 0x01f5da48 in +[NSException raise:format:arguments:] ()
#2 0x01f5d9b9 in +[NSException raise:format:] ()
#3 0x007e8c0d in CA::Layer::set_position(CA::Vec2<double> const&, bool) ()
#4 0x007def55 in -[CALayer setPosition:] ()
#5 0x037b07d3 in -[WebFixedPositionContent scrollOrZoomChanged:] ()
#6 0x00a5bfae in -[UIWebDocumentView _updateFixedPositionContent] ()
#7 0x00c66ff3 in -[UIWebBrowserView _updateFixedPositionContent] ()
#8 0x00a5b07e in -[UIWebDocumentView _didScroll] ()
#9 0x01fb6dea in -[NSObject performSelector:] ()
#10 0x01f207f1 in -[NSArray makeObjectsPerformSelector:] ()
#11 0x0091627d in -[UIScrollView(Static) _notifyDidScroll] ()
#12 0x009029ae in -[UIScrollView setContentOffset:] ()
#13 0x00909ac8 in -[UIScrollView _updatePanGesture] ()
#14 0x0090d3c0 in -[UIScrollView handlePan:] ()
#15 0x00b84e29 in _UIGestureRecognizerSendActions ()
#16 0x00b84133 in -[UIGestureRecognizer _updateGestureWithEvent:] ()
#17 0x00b853bf in -[UIGestureRecognizer _delayedUpdateGesture] ()
#18 0x00b87a21 in ___UIGestureRecognizerUpdate_block_invoke_0541 ()
#19 0x00b8797c in _UIGestureRecognizerApplyBlocksToArray ()
#20 0x00b803d7 in _UIGestureRecognizerUpdate ()
#21 0x008e51a2 in -[UIWindow _sendGesturesForEvent:] ()
#22 0x008e5532 in -[UIWindow sendEvent:] ()
我看过很多关于这个问题的问答,意识到苹果不鼓励这样做,但我没有看到任何提供替代方法的答案。
我的第一个问题:是否有其他方式可以实现相同的效果?
下面是我创建UIWebView的代码片段:
- (void) createWebView:(NSString*)url{
NSInteger requestedHeight = 480;
NSInteger requestedWidth = 640;
self.webContent = [[UIWebView alloc] initWithFrame: CGRectMake(0, self.frame.size.height, requestedWidth, requestedHeight)];
self.webContent.scrollView.userInteractionEnabled = NO;
self.webContent.scrollView.scrollEnabled = NO;
self.webContent.scrollView.bounces = NO;
NSURLRequest *urlRequest = [NSURLRequest requestWithURL:[NSURL URLWithString:url]];
[self.webContent loadRequest:urlRequest];
[self addSubview:self.webContent];
NSInteger calculatedHeight = self.webContent.frame.origin.y + self.webContent.frame.size.height;
NSInteger calculatedWidth = self.webContent.frame.origin.x + self.webContent.frame.size.width;
if (calculatedHeight > self.frame.size.height || calculatedWidth > self.frame.size.width){
self.frame = CGRectMake(self.frame.origin.x, self.frame.origin.y, MAX(self.frame.size.width, calculatedWidth), MAX(self.frame.size.height, calculatedHeight + 5));
}
}
如您所见,我禁用了UIWebView的滚动和用户输入。
我的第二个问题是:为什么UIWebView(或者说它的一个或多个子视图)在我明确禁用了滚动功能时仍然处理滚动?
我的第三个问题是:既然它似乎仍在处理滚动,是否有其他方法可以拦截或禁用发送到UIWebView的滚动通知?
如您所见,我实际上并不打算让用户与UIWebView的内容进行交互 - 只允许他们查看内容。
在这种情况下,可能的替代方案是在UIScrollView之外创建一个UIWebView,它对用户不可见,将其内容捕捉成图像,然后在UIImageView中显示内容。如果是这样,如何将UIWebView的内容捕捉成图像?
编辑: 我找到了一个非常简单的解决方案。基本上,加载您的UIWebView但不将其添加为子视图。当UIWebView完成加载时,使用下面的代码创建图像:
- (void)webViewDidFinishLoad:(UIWebView *)webView{
UIGraphicsBeginImageContext(self.webContent.bounds.size);
[self.webContent.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
[self.imageContent setImage:image];
}
我仍然希望听到问题1至3的答案。如果我们决定支持交互式UIWebView,这个解决方案将不起作用。
有什么建议吗?