Function 如何在Swift中创建具有完成处理程序的函数？

Function 如何在Swift中创建具有完成处理程序的函数？,function,swift,completionhandler,Function,Swift,Completionhandler,我只是好奇我将如何处理这个问题。如果我有一个函数，并且我希望在它完全执行时发生一些事情，我将如何将它添加到函数中？感谢假设您拥有从网络下载文件的下载功能，并希望在下载任务完成时收到通知 typealias CompletionHandler = (success:Bool) -> Void func downloadFileFromURL(url: NSURL,completionHandler: CompletionHandler) { // download code.

typealias CompletionHandler = (success:Bool) -> Void

func downloadFileFromURL(url: NSURL,completionHandler: CompletionHandler) {

    // download code.

    let flag = true // true if download succeed,false otherwise

    completionHandler(success: flag)
}

// How to use it.

downloadFileFromURL(NSURL(string: "url_str")!, { (success) -> Void in

    // When download completes,control flow goes here.
    if success {
        // download success
    } else {
        // download fail
    }
})

typealias CompletionHandler = (success:Bool) -> Void

func downloadFileFromURL(url: NSURL,completionHandler: CompletionHandler) {

    // download code.

    let flag = true // true if download succeed,false otherwise

    completionHandler(success: flag)
}

typealias CompletionHandler = (success:Bool) -> Void

func downloadFileFromURL(url: NSURL,completionHandler: CompletionHandler) {

    // download code.

    let flag = true // true if download succeed,false otherwise

    completionHandler(success: flag)
}

// How to use it.

downloadFileFromURL(NSURL(string: "url_str")!, { (success) -> Void in

    // When download completes,control flow goes here.
    if success {
        // download success
    } else {
        // download fail
    }
})

typealias CompletionHandler = (success:Bool) -> Void

func downloadFileFromURL(url: NSURL,completionHandler: CompletionHandler) {

    // download code.

    let flag = true // true if download succeed,false otherwise

    completionHandler(success: flag)
}

//下载代码

let flag=true

完成处理程序（success:flag）

func loadHealthCareList(completionClosure: (indexes: NSMutableArray)-> ()) {
      //some code here
      completionClosure(indexes: list)
}

healthIndexManager.loadHealthCareList { (indexes) -> () in
            print(indexes)
}

downloadFileFromURL(NSURL(string: "url_str")!)  { (success) -> Void in

  // When download completes,control flow goes here.
  if success {
      // download success
  } else {
    // download fail
  }
}

func yourFunctionName(finished: () -> Void) {

     print("Doing something!")

     finished()

}

     override func viewDidLoad() {

          yourFunctionName {

          //do something here after running your function
           print("Tada!!!!")
          }

    }

func method(arg: Bool, completion: (Bool) -> ()) {
    print("First line of code executed")
    // do stuff here to determine what you want to "send back".
    // we are just sending the Boolean value that was sent in "back"
    completion(arg)
}

method(arg: true, completion: { (success) -> Void in
    print("Second line of code executed")
    if success { // this will be equal to whatever value is set in this method call
          print("true")
    } else {
         print("false")
    }
})

    func methodName(completionBlock: () -> Void)  {

          print("block_Completion")
          completionBlock()
    }

    func methodName(completionBlock: () -> ())  {

        print("block_Completion")
        completionBlock()
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        
        methodName {

            print("Doing something after Block_Completion!!")
        }
    }