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Linux支持URLSession吗?

linux swift

lf_araujo · 技术社区 · 6 年前

curl -X GET --header 'Accept: text/plain' --header 'app_id: 8a7dd147' --header 'app_key: 7e7d022fbce6d8d4523eac3baa5bd04c' 'https://od-api.oxforddictionaries.com/api/v1/entries/en/ace'

返回Ace这个词的json数据。现在,在Ubuntu 18.04上,我尝试以下方法:

import Foundation
//var request = URLRequest(url: URL(string: "https://od-api.oxforddictionaries.com/api/v1/entries/en/love")!)

// TODO: replace with your own app id and app key
let appId = "8a7dd147"
let appKey = "7e7d022fbce6d8d4523eac3baa5bd04c"
let language = "en"
let word = "Ace"
let word_id = word.lowercased() //word id is case sensitive and lowercase is required
let url = URL(string: "https://od-api.oxforddictionaries.com/api/v1/entries/en/love")!  // \(language)/\(word_id)")!
var request = URLRequest(url: url)
request.addValue("application/json", forHTTPHeaderField: "Accept")
request.addValue(appId, forHTTPHeaderField: "app_id")
request.addValue(appKey, forHTTPHeaderField: "app_key")
//request.addValue("application/json", forHTTPHeaderField: "Content-Type")
print("passed request addValue")

let session = URLSession.shared
_ = session.dataTask(with: request, completionHandler: { data, response, error in
    if let response = response,
        let data = data,
        let jsonData = try? JSONSerialization.jsonObject(with: data, options: .mutableContainers) {
            print("about to give you a response")
        print(response)
        print(jsonData)
    } else {
        print(error)
        print(NSString.init(data: data!, encoding: String.Encoding.utf8.rawValue))
    }
}).resume()

或以下情况:

import Foundation

let params: [String: String] = ["app_id": "8a7dd147", "app_key": "7e7d022fbce6d8d4523eac3baa5bd04c"]

var request = URLRequest(url: URL(string: "https://od-api.oxforddictionaries.com/api/v1/entries/en/love")!)
request.httpMethod = "GET"
request.addValue("application/json", forHTTPHeaderField: "Accept")
request.addValue("8a7dd147", forHTTPHeaderField: "app_id")
request.addValue("7e7d022fbce6d8d4523eac3baa5bd04c", forHTTPHeaderField: "app_key")

URLSession.shared.dataTask(with: request, completionHandler: { data, response, error -> Void in
    print(response!)
    do {
        let json = try JSONSerialization.jsonObject(with: data!)
        print(json)
        print("we did it!")
    } catch {
        print("error")
    }
}).resume()

//task.resume()

但是没有人返回“爱”这个词的json信息。我一直在试着调试这个,但不知道出了什么问题。

它是否与操作系统相关,因此是一个bug?有人能在MacOS上测试一下吗。还是我遗漏了什么?

1 回复 | 直到 6 年前

user9335240 6 年前

URLSession 在后台线程上执行操作。当你结束一个多线程程序的主线程时,所有的线程都会被终止(除了在一些像Java这样的语言中你可以设置守护进程线程,守护进程线程可能是其他线程,但是程序的结束应该在该线程结束之后)。

因此,您的解决方案是延长主线程的生存期,如:

let group = DispatchGroup.init()

group.enter() // Use this before making anything that needs to be waited for
              // This manually add one to operation count in the dispatch group
URLSession.shared.dataTask(with: request, completionHandler: { data, response, error -> Void in
    defer {  // Defer makes all ends of this scope make something, here we want to leave the dispatch.
             // This is executed when the scope ends, even if with exception.


       group.leave() // Manually subtract one from the operation count
    }
    print(response!)
    do {
        let json = try JSONSerialization.jsonObject(with: data!)
        print(json)
        print("we did it!")
    } catch {
        print("error")
    }
}).resume()

group.wait()  // Wait for group to end operations.

但更好的是,在实际应用程序中,不要阻塞主线程,例如web应用程序,应用程序通常比请求更活跃,因此不需要干预,但要尽量避免阻塞用户( sleep DispatchGroup.wait 除非是在后台线程中,等等…)

Tiago Mendes chengsam 4 年前

您还可以使用以下代码:

// Avoid closing this project for 40 seconds
RunLoop.main.run(until: Date(timeIntervalSinceNow: 40))