dispatch-queue

问题 I have a DispatchQueue for a introViewController that shows a gif for 11 seconds and then display my login page... But also have a button that skip the intro and display the login. When I click it the time still running and when I am navigating in the app goes back to the login when the time ends. this is my class class GifClass: UIViewController { @IBOutlet weak var gifImage: UIImageView! @IBOutlet weak var skipButton: UIButton! override func viewDidLoad() { super.viewDidLoad() gifImage

问题 I did the simple test with DispatchQueue: DispatchQueue.global(qos: .background).sync { if Thread.isMainThread { print("Main thread") } } It printed out: Main thread Why does this code execute on the main thread? It should be performed on a background thread (it was added to a background queue), right? 回答1: Because it doesn't actually have to. You're blocking the main thread by using sync. iOS is choosing to just execute it on the main thread instead of bothering to switch to a background

问题 I am developing a Cocoapod library in which, i have to Call a function when timer fires. I am using that Cocoapod in an iOS App, Timer is not firing when App goes to background state private var timer : DispatchSourceTimer? = nil let queue = DispatchQueue(label: "sample.timer") timer = DispatchSource.makeTimerSource(queue : queue) timer?.setEventHandler { [weak self] in self?.sendData() } timer?.scheduleRepeating(deadline: .now(), interval: .seconds(5)) 回答1: The fact that you are using a GCD

问题 I am developing a Cocoapod library in which, i have to Call a function when timer fires. I am using that Cocoapod in an iOS App, Timer is not firing when App goes to background state private var timer : DispatchSourceTimer? = nil let queue = DispatchQueue(label: "sample.timer") timer = DispatchSource.makeTimerSource(queue : queue) timer?.setEventHandler { [weak self] in self?.sendData() } timer?.scheduleRepeating(deadline: .now(), interval: .seconds(5)) 回答1: The fact that you are using a GCD

问题 I am presenting the UIAlertController on the main thread as : class HelperMethodClass: NSObject { class func showAlertMessage(message:String, viewController: UIViewController) { let alertMessage = UIAlertController(title: "", message: message, preferredStyle: .alert) let cancelAction = UIAlertAction(title: "Ok", style: .cancel) alertMessage.addAction(cancelAction) DispatchQueue.main.async { viewController.present(alertMessage, animated: true, completion: nil) } } } And I am calling the method

问题 I have this block of code: DispatchQueue.main.asyncAfter(deadline: .now() + (delay * Double(isDelayAccounted.hashValue)) + extraDelay) { self.isShootingOnHold = false self.shoot() self.shootingEngine = Timer.scheduledTimer(timeInterval: (Double(60)/Double(self.ratePerMinute)), target: self, selector: #selector(ShootingEnemy.shoot), userInfo: nil, repeats: true) } Now, I want to be able to stop this thread from executing. How can I stop it from being executed? For instance, after 3 seconds, I

问题 I was going through the tutorial : https://www.raywenderlich.com/148513/grand-central-dispatch-tutorial-swift-3-part-1 And came across the definition of QoS class User-interactive . Its mentioned there that this should run on main thread. So, my question is then what is the difference between the DispatchQueue.global(qos: .userInteractive).async{} and DispatchQueue.main.async{} Thanks!! 回答1: The "quality of service" definitions are described here: https://developer.apple.com/library/content

问题 I am building an audio app based on the AudioUnit callback facility and a graph of audio processing nodes. I know that the callback is executed in a separate (high priority?) thread and therefore all interaction with my processing nodes, such as e.g. changing EQ parameters while playing, should be done in a thread safe manner. In other words, the nodes should be protected from modification while the audio callback chain is being executed. The way I understand it in terms of more low-level

问题 What I want to do is create an indirect queue targeting the main queue. dispatch_queue_t myQueue = dispatch_queue_create("com.mydomain.my-main-queue", NULL); dispatch_set_target_queue(myQueue, dispatch_get_main_queue()); My ultimate goal is to use the queue as the underlyingQueue property of an NSOperationQueue, because Apple's documentation clearly states not to use dispatch_get_main_queue(). Though using an indirect queue it technically is following the documentation. The reason for all

问题 I fetch data and display in a tableView, the problem is the data is not executing in the correct order. I have tried: for case let child as DataSnapshot in data!.children.reversed() { let newDispatchGroup = DispatchGroup() let commentID = child.key let uid = child.childSnapshot(forPath: "UID").value as! String let commentText = child.childSnapshot(forPath: "Comment").value! let timeStamp = child.childSnapshot(forPath: "timeStamp").value! let date = ConvertDate(mediaTimestamp: timeStamp as!