如何可靠地检测 UIWebView 中的链接点击?

问题描述

我有一个 UIWebView，当用户点击链接时我需要做一些事情.有一个委托回调可用于检测点击:

I have a UIWebView and I need to do something when user taps a link. There’s a delegate callback that can be used to detect the taps:

- (BOOL) webView: (UIWebView*) webView
    shouldStartLoadWithRequest: (NSURLRequest*) request
    navigationType: (UIWebViewNavigationType) navigationType
{
    if (navigationType == UIWebViewNavigationTypeLinkClicked) {
        …
    }
}

问题是这段代码不能处理所有的链接点击.例如，一个普通的 Google 搜索结果页面对链接做了一些奇怪的事情:

The problem is that this code doesn’t handle all link clicks. As an example, a plain Google Search results page does something weird with the links:

<a href="http://example.com/" class="l" onmousedown="return rwt(…)">
    <em>Link Text</em>
</a>

rwt 函数导致链接在点击时不会触发 UIWebViewNavigationTypeLinkClicked 事件.有没有办法可靠地检测落入导航到其他页面"存储桶的所有事件?

The rwt function results in the links not triggering the UIWebViewNavigationTypeLinkClicked event when tapped. Is there a way to reliably detect all events that fall into the "navigate to some other page" bucket?

推荐答案

到目前为止，我已经得出以下解决方案.首先，我在加载时将一些 JS 代码注入到页面中:

So far I have arrived at the following solution. First, I inject some JS code into the page when loaded:

function reportBackToObjectiveC(string)
{
    var iframe = document.createElement("iframe");
    iframe.setAttribute("src", "callback://" + string);
    document.documentElement.appendChild(iframe);
    iframe.parentNode.removeChild(iframe);
    iframe = null;
}

var links = document.getElementsByTagName("a");
for (var i=0; i<links.length; i++) {
    links[i].addEventListener("click", function() {
        reportBackToObjectiveC("link-clicked");
    }, true);
}

当用户点击链接时，由于 webView:shouldStartLoadWithRequest: navigationType: 委托调用，我提前知道了:

When user taps a link, I know it in advance thanks to the webView:shouldStartLoadWithRequest: navigationType: delegate call:

if ([[[request URL] scheme] isEqualToString:@"callback"]) {
    [self setNavigationLeavingCurrentPage:YES];
    return NO;
}

然后，如果另一个请求来了并且 _navigationLeavingCurrentPage 为真，我知道用户点击了一个链接，即使导航类型标志是 UIWebViewNavigationTypeOther.我仍然需要对解决方案进行广泛的测试，因为我担心它会导致一些误报.

Then if another request comes and _navigationLeavingCurrentPage is true, I know the user has clicked a link even though the navigation type flag is UIWebViewNavigationTypeOther. I still have to test the solution extensively, for I’m afraid that it will lead to some false positives.

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