How to make one code run only after the other is done in Swift

Question

I am new to async and sync mechanism. In my code I have to perform one code line only after the other is done. It looks something like this:

    func something(){

    let workerQueue = DispatchQueue.global(qos: .userInitiated)
            workerQueue.async{
         let info = getInfoFromTheWeb()//I need the info value in order to perform the next line
         saveToDB(info: info)

      DispatchQueue.main.async {
       //update a label text in the ui after getting and saving that info
      }

    }
}

Your professional thoughts please..

Answer 1

Your should DispatchGroup. By using DispatchGroup one function/line of code will wait until the other function completes execution.

For example

let myGroup = DispatchGroup()
   myGroup.enter()
   let info = getInfoFromTheWeb()

When you get info from simple call

myGroup.leave()

When your call leave() function following code will be execute

myGroup.notify(queue: DispatchQueue.main) {

            saveToDB(info: info)
           /// Update UI elements
        }