dispatchworkitem

问题 I have several Dispatch work items to execute on a queue i don't want to redeclare the codes, i want to pass them to an array or list of DispatchWorkItems and then inject it to a dispatch queue is there any way to achieve this ? func executeDispatchWorkItem(url: String, completion : @escaping (Result<String,Error>)-> Void,beganHandler : @escaping (String)-> Void){ do { beganHandler("\(url) Began to execute ") let content = try String(contentsOf:URL(string: url)!) completion(.success(content))

问题 I am currently playing around with Grand Central Dispatch and discovered a class called DispatchWorkItem . The documentation seems a little incomplete so I am not sure about using it the right way. I created the following snippet and expected something different. I expected that the item will be cancelled after calling cancel on it. But the iteration continues for some reason. Any ideas what I am doing wrong? The code seems fine for me. @IBAction func testDispatchItems() { let queue =