swift iOS从异步中获取价值(发布数据)

Question

我有一个问题是在异步过程中获取值.

我的班级是:

public class PostService: NSObject {

var result : String = String()

//this is my function


func request(var dataPost : String, var destination : String)->String{

    let request = NSMutableURLRequest(URL: NSURL(string: destination as String)!)
    request.HTTPMethod = "POST"
    let postString = dataPost
    request.HTTPBody = postString.dataUsingEncoding(NSUTF8StringEncoding)
    let task = NSURLSession.sharedSession().dataTaskWithRequest(request) {
        data, response, error in

        if error != nil {
            println("error=\(error)")
            return
        }

        let responseString = NSString(data: data, encoding: NSUTF8StringEncoding)

        self.result = responseString as String!

    }

    task.resume()

//problem is here that result will fill after async

    return self.result       
}

}

//我在这里使用这个功能

override func viewDidLoad() {
    super.viewDidLoad()
    var dataPost :String="Name=Ali"
    var dest : String =  "http://example.com/api/getUserName"
    var result = Post.request(dataPost, destination: dest)
    lbltext.text = result as String!
}

Answer 1

func request(var dataPost : String, var destination : String, successHandler: (response: String) -> Void)->String{
    let request = NSMutableURLRequest(URL: NSURL(string: destination as String)!)
    request.HTTPMethod = "POST"
    let postString = dataPost
    request.HTTPBody = postString.dataUsingEncoding(NSUTF8StringEncoding)
    let task = NSURLSession.sharedSession().dataTaskWithRequest(request) {
        data, response, error in

        if error != nil {
            println("error=\(error)")
            return
        }

        let responseString = NSString(data: data, encoding: NSUTF8StringEncoding)

        //self.result = responseString as String!
        successHandler(responseString as String!);

    }

    task.resume()
}

override func viewDidLoad() {
    super.viewDidLoad()
    var dataPost :String="Name=Ali"
    var dest : String =  "http://example.com/api/getUserName"
    Post.request(dataPost, destination: dest, successHandler: {
        (response) in
        lbltext.text = response;
    });

}

像下面这样的东西.基本上,您传递成功处理程序的回调并在回调函数内执行操作.

异步操作意味着它们独立于代码的字节序列而发生.这就是为什么当你进行异步调用时,你不能返回一个值.当异步调用在后台(或另一个线程)中运行时,代码的原始序列会运行.这就是成功和错误处理程序存在的原因.它们允许您在异步请求完成时运行一大块代码.

PS请重新格式化您的问题,并确保所有代码都正确缩进.