Swift

斯威夫特更严格;你想保护自己免受 nil 指针和期权：

Swift is more stringent ; you want to protect yourself against nil pointers and optionals:

• 检查 webView 实际上是否有请求


• 检查请求实际上是否有 NSCachedURLResponse


• 类型 - 检查对 NSHTTPURLResponse的反应

• check that the webView actually has a request
• check that the request actually has a NSCachedURLResponse
• type-check the response against NSHTTPURLResponse

func webViewDidFinishLoad(webView: UIWebView) {
    if let request = webView.request {
        if let resp = NSURLCache.sharedURLCache().cachedResponseForRequest(request) {
            if let response = resp.response as? NSHTTPURLResponse {
                print(response.allHeaderFields)
            }
        }
    }
}