异步请求后如何调用主线程答案

【问题标题】：How to call Main Thread after an asynchronous request异步请求后如何调用主线程
【发布时间】：2018-01-24 17:57:51
【问题描述】：

当我发出以下网络请求时，打印语句似乎在异步之前触发。请求已完成。我只在异步请求完成后才尝试调用主线程。

func getRating (articleID: String) {
    let endPointURL = "http://www.smarttapp.com/DesktopModules/DnnSharp/DnnApiEndpoint/Api.ashx?method=GetRating"
    let encodedarticleIDURL = endPointURL.addingPercentEncoding(withAllowedCharacters: CharacterSet.urlQueryAllowed)!
    let myURL = URL(string: encodedarticleIDURL)

    Alamofire.request(
        myURL!,
        parameters: ["articleID": articleID]
        )
        .responseData { response in
            guard response.result.isSuccess else {
                return
            }

            if let data = response.data, let myDataString = String(data: data, encoding: .utf8) {
                print("MyDataString is: \(myDataString)")
                let newRating = Double(myDataString)!
                self.post.rating = newRating
                print(newRating)
            }
    }
    DispatchQueue.main.async {
        print("Final value \(self.post.rating)")
        self.networkingState = .finishedSearching
        self.tableView.reloadData()
    }
}

【问题讨论】：

标签： ios swift alamofire

【解决方案1】：

您需要在 Alamofire 响应完成块中执行主线程，它应该可以工作

Alamofire.request(
        myURL!,
        parameters: ["articleID": articleID]
        )
        .responseData { response in
            guard response.result.isSuccess else {
               return
            }

            if let data = response.data, let myDataString = String(data: data, encoding: .utf8) {
                print("MyDataString is: \(myDataString)")
                let newRating = Double(myDataString)!
                self.post.rating = newRating
                print(newRating)
            }

         DispatchQueue.main.async {
        print("Final value \(self.post.rating)")
        self.networkingState = .finishedSearching
        self.tableView.reloadData()
    }
    }

【讨论】：