ios 如何清除 UIWebView
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原文地址: http://stackoverflow.com/questions/6576154/
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How To Clear A UIWebView
提问by Tom Cuzz
I am very new to the whole programming business, and was wondering if there is any way to clear the contents of a UIWebViewin iphone programming, so that the loading symbol for the next view is not showing up in front of the last view.
Many Thanks,
Thomas
我对整个编程业务很陌生，想知道是否有什么方法可以清除UIWebViewiphone编程中a的内容，这样下一个视图的加载符号就不会出现在上一个视图的前面。非常感谢，托马斯
回答by Constantino Tsarouhas
Try setting the URL to about:blankand reload the page.
尝试将 URL 设置为about:blank并重新加载页面。
回答by 2cupsOfTech
Just load an empty html string into it
只需将一个空的 html 字符串加载到其中
[self.webView loadHTMLString:@"" baseURL:nil];
[self.webView loadHTMLString:@"" baseURL:nil];
回答by Bill Patterson
Answer extension for documentation purposes to maybe help someone else:
出于文档目的的回答扩展可能会帮助其他人：
I had the same desire (clear content before loading next url) but had a UIWebView delegate set to receive webviewDidFinishLoad:(UIWebView)webviewmessage and update another part of UI in response.
我有同样的愿望（在加载下一个 url 之前清除内容）但是有一个 UIWebView 委托设置为接收webviewDidFinishLoad:(UIWebView)webview消息并更新 UI 的另一部分作为响应。
Problem: the call to clear the content to alsocalled delegate method, so getting false-hits (that is, getting call when clear is done, too, but delegate is coded to expect call only when real content is loaded).
问题：清除内容的调用也调用了委托方法，因此会出现错误命中（即，清除完成后也调用，但委托被编码为仅在加载实际内容时才期望调用）。
Solution: use a known URL for clear, and have webviewDidFinishLoad:ignore calls made when that URL is finished:
解决方案：使用已知 URL 进行清除，并webviewDidFinishLoad:忽略该 URL 完成后的调用：
- (void) startLoadOfNextURL:(NSURL*)url
{
// clear:
[self.webView loadHTMLString:@"" baseURL:nil];
// Load real next URL
NSURLRequest* request = [NSURLRequest requestWithURL:url];
[self.webView loadRequest:request];
}
- (void)webViewDidFinishLoad:(UIWebView *)webView
{
NSLog(@"WebView finished loading: %@", webView);
if ([self.webView.request.URL.absoluteString isEqualToString:@"about:blank"]) {
NSLog(@" This is Blank. Ignoring as false event.");
}
else {
NSLog(@" This is a real url");
[self updateUIInSomeWay];
}
}
Note: using this:
注意：使用这个：
[self.webView loadHTMLString:@"about:blank" baseURL:nil];
actually causes the words "about:blank" to appear as text in the webview's content pane!
实际上会导致“about:blank”这个词在 webview 的内容窗格中显示为文本！
Final complication: In practice, with my two [webview load...]calls so close together, I was finding that instead of a "loaded" event for the clear, the webview was actually canceling it in favor of the second request and calling webView: didFailLoadWithError:for the first load request. Thus, I had to put similar code in that event:
最后的复杂性：在实践中，由于我的两个[webview load...]调用如此接近，我发现 webview 实际上取消了它而不是一个“加载”事件以支持第二个请求并调用webView: didFailLoadWithError:第一个加载请求。因此，我不得不在该事件中放置类似的代码：
- (void)webView:(UIWebView *)webView didFailLoadWithError:(NSError *)error
{
NSLog(@"WebView error on: %@", webView);
NSLog(@"Error is: %@", error);
NSURL* failingURL = [error.userInfo objectForKey:@"NSErrorFailingURLKey"];
if ([failingURL.absoluteString isEqualToString:@"about:blank"]) {
NSLog(@" This is Blank. Ignoring.");
}
else {
NSLog(@" This is a real URL.");
[self doSomethingAboutError];
}
}
回答by neoneye
Swift, Xcode 7 beta 5
斯威夫特，Xcode 7 测试版 5
webView.loadRequest(NSURLRequest(URL: NSURL(string: "about:blank")!))
回答by ViJay Avhad
Swift 4.0 , XCODE 9
斯威夫特 4.0 , Xcode 9
webView.loadRequest(URLRequest.init(url: URL.init(string: "about:blank")!))
回答by AbdulRehman Warraich
Same answer in Swift 4.2, xCode 10
Swift 4.2 中的相同答案，xCode 10
if let clearURL = URL(string: "about:blank") {
myWebView.loadRequest(URLRequest(url: clearURL))
}
