RevokableTask adds a task delayed to the main queue which can be revoked or cancelled.

RevokableTask.swift

typealias TaskHandler = () -> ()

class RevokableTask {
    private(set) var isCancelled: Bool = false
    private(set) var task: TaskHandler
    private(set) var delayTime: DispatchTime
    private(set) var identifier: String
    
    init(delayInSeconds: Double, task: @escaping TaskHandler) {
        self.task = task
        self.delayTime = .now() + delayInSeconds
        self.identifier = UUID().uuidString
    }
    
    func execute() {
        DispatchQueue.main.asyncAfter(deadline: self.delayTime) {
            if !self.isCancelled {
                self.task()
            }
        }
    }
    
    func revoke() {
        self.isCancelled = true
    }
}

Sample.swift

  let task = RevokableTask(delayInSeconds: 120) {
      print("This task must not be executed...")
  }

  let task2 = RevokableTask(delayInSeconds: 120) {
      print("Task is executing...")
  }
  
  task.execute()
  task2.execute()
  task.revoke()