我在异步过程中获取值时遇到问题。
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
}
}
//我在这里使用这个函数
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!
}
最佳答案:
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。基本上,您传递一个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发生。这就是为什么当您进行异步调用时,不能返回值的原因。当异步调用在后台(或在另一个线程中)运行时,代码的原始序列将运行。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段代码。
另外,请重新格式化您的问题,并确保所有代码都正确缩进。