Wait for asynchronous block before continuing

Question

I have a function lets call it "a" that runs some code and then returns a string "x" is updated in an asynchronous code block and then returned.

How would I go about making the program wait to return x until after the asynchronous code runs?

func a() -> String {

    //code
    //code
    var x: String
    async block {

    x = "test"
    }
    return x
}

Answer 1

You can use completion closure for this

func a(completion: @escaping (_ value:String)->()) {
    var x: String = ""
    async block {
      x = "test"
      completion(x) //when x has new value
    }
}

//Call like this (value will be executed when the completion block is returned

a { (value) in
     print(value)
  }