如何防止命令行工具在异步操作完成之前退出 [英] How to prevent a Command Line Tool from exiting before asynchronous operation completes

问题描述

在swift 2命令行工具(main.swift)中，我具有以下内容:

In a swift 2 command line tool (main.swift), I have the following:

import Foundation
print("yay")

var request = HTTPTask()
request.GET("http://www.stackoverflow.com", parameters: nil, completionHandler: {(response: HTTPResponse) in
    if let err = response.error {
        print("error: \(err.localizedDescription)")
        return //also notify app of failure as needed
    }
    if let data = response.responseObject as? NSData {
        let str = NSString(data: data, encoding: NSUTF8StringEncoding)
        print("response: \(str)") //prints the HTML of the page
    }
})

控制台显示是"，然后退出(程序以退出代码结束:0)，似乎从未等待请求完成.我该如何防止这种情况发生?

The console shows 'yay' and then exits (Program ended with exit code: 0), seemingly without ever waiting for the request to complete. How would I prevent this from happening?

代码正在使用 swiftHTTP

我认为我可能需要

I think I might need an NSRunLoop but there is no swift example

推荐答案

我意识到这是一个老问题，但这是我最后的解决方案.使用 DispatchGroup .

I realize this is an old question, but here is the solution I ended on. Using DispatchGroup.

let dispatchGroup = DispatchGroup()

for someItem in items {
    dispatchGroup.enter()
    doSomeAsyncWork(item: someItem) {
        dispatchGroup.leave()
    }
}

dispatchGroup.notify(queue: DispatchQueue.main) {
    exit(EXIT_SUCCESS)
}
dispatchMain()

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