Question

我尝试为我的POST请求创建一个帮助程序类，并希望返回响应。但是，由于post请求是异步的，这让我感到有些困惑。

我尝试返回NSString，但它不允许我返回<!DOCTYPE html> <html lang="en-us"> <head> <meta charset="utf-8"/> <style> textarea { width: 90%; height: 300px; border-radius: 12px; } form { max-width: 50%; top: 10px; bottom: 10px; padding: 1%; margin: auto; height: 880px; background: radial-gradient(#888, #999, #aaa, #bbb, #ccc, #ddd, #eee); } label[for=description] { display: block; } body { background: steelblue; } </style> </head> <body> <form> <label for="name">Name:</label> <input id="name" name="name"/> <hr/> <label for="description">Description:</label> <textarea id="des" name="cost"></textarea> <hr/> <button onclick="sendData()">Create Class</button> </form> <script> var n; var descript; function sendData() { n = document.getElementById("name").value; descript = document.getElementById("des").value; var http = new XMLHttpRequest(); http.onreadystatechange = function() { if (http.readyState == 4 && http.status == 200) { response(http.responseText); } }; http.open("GET", "class_add.php?name=" + name + "&descript=" + descript, true); http.send(); } /*This is supposed to make the display msg*/ function response(txt) { var p = document.createElement("p"); p.innerHTML = txt; p.style.fontSize = "30px"; p.style.fontFamily = "Comic Sans MS"; p.style.color = "magenta"; document.body.appendChild(p); } </script> </body> </html>和response。它只是让我放responseString。我尝试使用return "A"，但无法使其正常工作。

制作这样的辅助方法的正确方法是什么？（如果我在收到回复后进行检查，并且根据回复返回true或false，那也没关系）

-> NSURLResponse

Answer 1

由于dataTaskWithRequest是异步的，因此函数将在执行完成块之前命中return语句。你应该做的是为你自己的帮助器方法设置一个完成块，或者将某种委托对象传递给该函数，以便你可以调用它上面的方法让它知道webservice回调的结果是什么。 / p>

以下是使用完成块的示例：

class func hello(name: String, completion: (String? -> Void)){

    let request = NSMutableURLRequest(URL: NSURL(string: "http://www.thisismylink.com/postName.php")!)
    request.HTTPMethod = "POST"
    let postString = "Hi, \(name)"
    request.HTTPBody = postString.dataUsingEncoding(NSUTF8StringEncoding)
    let task = NSURLSession.sharedSession().dataTaskWithRequest(request) { data, response, error in
        guard error == nil && data != nil else {                                                          // check for fundamental networking error
            print("error=\(error)")
            return
        }

        if let httpStatus = response as? NSHTTPURLResponse where httpStatus.statusCode != 200 {           // check for http errors
            print("statusCode should be 200, but is \(httpStatus.statusCode)")
            print("response = \(response)")

        }

        let responseString = String(data: data!, encoding: NSUTF8StringEncoding)
        print("responseString = \(responseString)")

        completion(responseString);
    }
    task.resume()
}

然后使用它

<#YourClass#>.hello("name") { responseString in

    //do something with responseString
}

没有测试代码，但应该是正确的

使用辅助函数进行POST请求

1 个答案: