下面是Xamarin iOS版的drawnonward的答案。

class WebviewDelegate : UIWebViewDelegate {
    public override bool ShouldStartLoad (UIWebView webView, NSUrlRequest request, UIWebViewNavigationType navigationType) {
        if (navigationType == UIWebViewNavigationType.LinkClicked) {
            UIApplication.SharedApplication.OpenUrl (request.Url);
            return false;
        }
        return true;
    }
}

下面是Xamarin iOS版的drawnonward的答案。

class WebviewDelegate : UIWebViewDelegate {
    public override bool ShouldStartLoad (UIWebView webView, NSUrlRequest request, UIWebViewNavigationType navigationType) {
        if (navigationType == UIWebViewNavigationType.LinkClicked) {
            UIApplication.SharedApplication.OpenUrl (request.Url);
            return false;
        }
        return true;
    }
}

在Swift中，你可以使用以下代码:

extension YourViewController: UIWebViewDelegate {
    func webView(_ webView: UIWebView, shouldStartLoadWith request: URLRequest, navigationType: UIWebView.NavigationType) -> Bool {
        if let url = request.url, navigationType == UIWebView.NavigationType.linkClicked {
            UIApplication.shared.open(url, options: [:], completionHandler: nil)
            return false
        }
        return true
    }

}

确保检查了URL值和navigationType。

如果有人想知道，Drawnonward的解决方案在Swift中是这样的:

func webView(webView: UIWebView!, shouldStartLoadWithRequest request: NSURLRequest!, navigationType: UIWebViewNavigationType) -> Bool {
    if navigationType == UIWebViewNavigationType.LinkClicked {
        UIApplication.sharedApplication().openURL(request.URL)
        return false
    }
    return true
}

其他答案有一个问题:它们依赖于你所做的操作，而不是链接本身来决定是在Safari中加载还是在webview中加载。

有时候这正是你想要的，这很好;但有些时候，特别是当你的页面中有锚点链接时，你想在Safari中只打开外部链接，而不是内部链接。在这种情况下，您应该检查URL。请求的主机属性。

我使用这段代码来检查正在解析的URL中是否有主机名，或者它是否是嵌入的html:

- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType {
    static NSString *regexp = @"^(([a-zA-Z]|[a-zA-Z][a-zA-Z0-9-]*[a-zA-Z0-9])[.])+([A-Za-z]|[A-Za-z][A-Za-z0-9-]*[A-Za-z0-9])$";
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", regexp];

    if ([predicate evaluateWithObject:request.URL.host]) {
        [[UIApplication sharedApplication] openURL:request.URL];
        return NO; 
    } else {
        return YES; 
    }
}

当然，您可以调整正则表达式以满足您的需要。

将这个添加到UIWebView委托:

(经过编辑以检查导航类型。你也可以通过file:// requests传递相对链接)

- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType {
    if (navigationType == UIWebViewNavigationTypeLinkClicked ) {
        [[UIApplication sharedApplication] openURL:[request URL]];
        return NO;
    }

    return YES;
}

斯威夫特版本:

func webView(webView: UIWebView, shouldStartLoadWithRequest request: NSURLRequest, navigationType: UIWebViewNavigationType) -> Bool {
        if navigationType == UIWebViewNavigationType.LinkClicked {
            UIApplication.sharedApplication().openURL(request.URL!)
            return false
        }
        return true
    }

Swift 3版本:

func webView(_ webView: UIWebView, shouldStartLoadWith request: URLRequest, navigationType: UIWebViewNavigationType) -> Bool {
    if navigationType == UIWebViewNavigationType.linkClicked {
        UIApplication.shared.openURL(request.url!)
        return false
    }
    return true
}

Swift 4版本:

func webView(_ webView: UIWebView, shouldStartLoadWith request: URLRequest, navigationType: UIWebView.NavigationType) -> Bool {
    guard let url = request.url, navigationType == .linkClicked else { return true }
    UIApplication.shared.open(url, options: [:], completionHandler: nil)
    return false
}

更新

由于openURL在iOS 10中已弃用:

- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType {
        if (navigationType == UIWebViewNavigationTypeLinkClicked ) {
            UIApplication *application = [UIApplication sharedApplication];
            [application openURL:[request URL] options:@{} completionHandler:nil];
            return NO;
        }

        return YES;
}