NSTimer不要在选择器中调用方法

Question

Hello

I'm trying to execute a task in background because I need to while the application is running being pulling data from the server. I write the code in the AppDelegate.swift, this is the code that i wrote:

    class AppDelegate: UIResponder, UIApplicationDelegate, UISplitViewControllerDelegate {

        var window: UIWindow?
        let manager = AppManager.manager
        var timer: NSTimer? = nil

        func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
            // Override point for customization after application launch.
            self.timer = NSTimer(timeInterval: 1.0, target: self, selector: "UpdateDeviceData:", userInfo: nil, repeats: true)
           return true
         }                                                                                                           
         func UpdateDeviceData(timer:NSTimer) {
            dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), { () -> Void in
               print("do some background task")

               dispatch_async(dispatch_get_main_queue(), { () -> Void in
                  print("update some UI")

            })
        })
    }

}

I put a breakpoint in the line "print" and it never being executed.

Please any idea about what could be the problem?

I'm using Xcode 7 beta and Swift

Answer 1

You need to schedule the timer on a run loop - you're just assigning it to a variable. Try using the class method + scheduledTimerWithTimeInterval:target:selector:userInfo:repeats: -

so

NSTimer.scheduledTimerWithTimeInterval(1.0, target: self, selector: "UpdateDeviceData:", userInfo: nil, repeats: true)