函数开头的返回值[重复]

Question

当我调用这个函数时，函数返回值，然后做所有其他事情。我怎样才能使函数返回其他事物的值结束。

    func register(parameters : [String : String]) -> Int {

    let headers = [
        "content-type": "application/json",
        "cache-control": "no-cache",
    ]
    var statuscode = 0
    var postD = NSData();
    do {
        let postData = try NSJSONSerialization.dataWithJSONObject(parameters, options: NSJSONWritingOptions.PrettyPrinted)
        postD = postData;
    }catch let error as NSError{
        print(error.description)
    }
    var request = NSMutableURLRequest(URL: NSURL(string: "\(hostUrl)/users")!,
                                      cachePolicy: .UseProtocolCachePolicy,
                                      timeoutInterval: 10.0)

    request.HTTPMethod = "POST"
    request.allHTTPHeaderFields = headers
    request.HTTPBody = postD

    let session = NSURLSession.sharedSession()
    let dataTask = session.dataTaskWithRequest(request, completionHandler: { (data, response, error) -> Void in
        if (error != nil) {
            print(error)
        } else {
            let httpResponse = response as? NSHTTPURLResponse
            statuscode = httpResponse!.statusCode
            print("AFTER HTTP RESPONSE STATUSCODE = \(statuscode)")

        }
    })

    dataTask.resume()
    return statuscode
}

我这样调用这个函数：

let statuscode = client.register(parameters)
        print("denemeeeeeeeeeeeeee\(statuscode)")

这是我的输出

denemeeeeeeeeeeeeee0
AFTER HTTP RESPONSE STATUSCODE = 400

Answer 1

NSURLSession是一个异步API，所以恐怕你的函数总是在数据请求完成之前返回。您将不得不考虑替代方法。例如，您的 register 方法可能会收到您在数据任务完成时调用的完成闭包。

Answer 2

你需要实现一个callback 函数来处理这种事情：

func register(parameters : [String : String], callback: ((success: Bool, response: NSHTTPURLResponse)->Void){

let headers = [
    "content-type": "application/json",
    "cache-control": "no-cache",
]
var postD = NSData();
do {
    let postData = try NSJSONSerialization.dataWithJSONObject(parameters, options: NSJSONWritingOptions.PrettyPrinted)
    postD = postData;
}catch let error as NSError{
    print(error.description)
}
var request = NSMutableURLRequest(URL: NSURL(string: "\(hostUrl)/users")!,
                                  cachePolicy: .UseProtocolCachePolicy,
                                  timeoutInterval: 10.0)

request.HTTPMethod = "POST"
request.allHTTPHeaderFields = headers
request.HTTPBody = postD

let session = NSURLSession.sharedSession()
let dataTask = session.dataTaskWithRequest(request, completionHandler: { (data, response, error) -> Void in
    if (error != nil) {
        print(error)
    } else {

        let httpResponse = response as? NSHTTPURLResponse
        callback?(success: true, response: httpResponse)


    }
})

dataTask.resume()
}

在你的函数调用中：

client.register(parameters, callback: { (success, response) in
     var statuscode = 0
     statuscode = response!.statusCode
     print("AFTER HTTP RESPONSE STATUSCODE = \(statuscode)")
})

如果这还不足以实现您想要做的事情，您还可以查看dispatch groups。

祝你好运。