Creating a concurrent queue let concurrentQueue = DispatchQueue(label: “queuename”, attributes: .concurrent) concurrentQueue.sync { } Create a serial queue let serialQueue = DispatchQueue(label: “queuename”) serialQueue.sync { } Get main queue asynchronously DispatchQueue.main.async { } Get main queue synchronously DispatchQueue.main.sync { } To get one of the background thread DispatchQueue.global(qos: .background).async { } Xcode 8.2 beta 2: … Read more
You can use dispatch groups to fire an asynchronous callback when all your requests finish. Here’s an example using dispatch groups to execute a callback asynchronously when multiple networking requests have all finished. override func viewDidLoad() { super.viewDidLoad() let myGroup = DispatchGroup() for i in 0 ..< 5 { myGroup.enter() Alamofire.request(“https://httpbin.org/get”, parameters: [“foo”: “bar”]).responseJSON { … Read more
This is a perfectly acceptable and thread-safe way to create an instance of your class. It may not technically be a “singleton” (in that there can only ever be 1 of these objects), but as long as you only use the [Foo sharedFoo] method to access the object, this is good enough.
I use dispatch_after so often that I wrote a top-level utility function to make the syntax simpler: func delay(delay:Double, closure:()->()) { dispatch_after( dispatch_time( DISPATCH_TIME_NOW, Int64(delay * Double(NSEC_PER_SEC)) ), dispatch_get_main_queue(), closure) } And now you can talk like this: delay(0.4) { // do stuff } Wow, a language where you can improve the language. What could … Read more