iPhone / iPad UIWebView需要是活动视图来渲染吗？ [英] Does iPhone/iPad UIWebView need to be active view to render?

问题描述

我需要将屏幕外的网页呈现为位图，然后向用户显示位图。这可以通过主线程上的简单代码完成，如下所示：

I need to render a web page offscreen to a bitmap, then show the bitmap to the user. Can this be done with simple code on the main thread like this:

NSString *urlAddress = @"http://www.google.com";
NSURL *url = [NSURL URLWithString:urlAddress];
NSURLRequest *requestObj = [NSURLRequest requestWithURL:url];
[offscreenWebView loadRequest:requestObj];

或者我是否需要将UIWebView附加到活动视图？

Or do I need to attach the UIWebView to an active view?

在Android中，除非视图是活动视图的一部分，否则Web视图似乎不会呈现。因此，要在Android中执行此任务，我需要创建一个视图层次结构，为Web渲染器创建一个活动视图，然后在其上面放置另一个视图以让它在屏幕外绘制。

In Android, the web view seems not to render unless it is part of an active view. So to do this task in Android, I need to create a view hierarchy, create an active view for the web renderer, and then put another view on top of it to let it draw offscreen.

推荐答案

我自己一直在努力解决这个问题。除非将UIWebView添加到UIWindow对象，否则它不会呈现。但是，这不一定是您用来显示应用程序的窗口。你可以创建一个单独的UIWindow对象，并将UIWebView附加到它，它将呈现得很好。但是，UIWebView渲染是一个缓慢的过程，因此它在准备好之前会有一个短暂的延迟。完成后，它会将webViewDidFinishLoad方法触发到其委托。

I struggled with this problem for a while myself. UIWebView will not render unless it is added to a UIWindow object. However, this does not have to be the window you are using to show your app. You can make a separate UIWindow object, and attach the UIWebView to that and it will render just fine. However, UIWebView rendering is a slow process, so it will have a short delay before it is ready. When it is done, it will fire the webViewDidFinishLoad method to its delegate.

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