Atomic class from https://www.objc.io/blog/2018/12/18/atomic-variables/

Atomic.swift

// FROM: https://www.objc.io/blog/2018/12/18/atomic-variables/

final class Atomic<A> {
   private let queue = DispatchQueue(label: "Atomic serial queue")
   private var _value: A
   init(_ value: A) {
      self._value = value
   }

   var value: A {
      get {
         return queue.sync { self._value }
      }
   }

   func mutate(_ transform: (inout A) -> ()) {
      queue.sync {
         transform(&self._value)
      }
   }
}

Use like :-

let x = Atomic<Int>(5)
x.mutate { $0 += 1 }