Know when an iteration over array with async method is finished

Question

Lets say i have an array of strings, and i call an async method that returns an int from it. I want to know when i have those int values in my array of ints.

let rndStrings = ["a", "b", "c"]
var rndInts = [Int]()
rndStrings.forEach { rndString in 
   someAsyncMethod { intResult in
     rndInts.append(intResult)
   }
}

I want to wait until rndInts has all 3 values

Answer 1

Don't wait. Get notified with DispatchGroup.

let rndStrings = ["a", "b", "c"]
let group = DispatchGroup()
var rndInts = [Int]()
rndStrings.forEach { rndString in 
   group.enter()
   someAsyncMethod { intResult in
     rndInts.append(intResult)
     group.leave()
   }
}
group.notify(queue: DispatchQueue.main) {
   print("finished")
}