Check Device screen On or Off in iOS

Helle there, I'm using the code below to check whether the device's screen is on or off. I got this code from this SO post.

Code:

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
        // Override point for customization after application launch.

        CFNotificationCenterAddObserver(CFNotificationCenterGetDarwinNotifyCenter(), nil, displayStatusChanged, "com.apple.springboard.lockcomplete", nil, CFNotificationSuspensionBehavior.deliverImmediately)
        //CFNotificationCenterAddObserver(CFNotificationCenterGetDarwinNotifyCenter(), nil, displayStatusChanged, "com.apple.springboard.lockstate", nil, CFNotificationSuspensionBehavior.deliverImmediately)

        return true
    }
}//AppDelegate class end here

func displayStatusChanged(center:CFNotificationCenter,observer: UnsafeMutableRawPointer?,name:CFString,object: UnsafeRawPointer?,userInfo:CFDictionary) -> Void {

}

But I got this error:

Cannot convert value of type '(CFNotificationCenter, UnsafeMutableRawPointer?, CFString, UnsafeRawPointer?, CFDictionary) -> Void' to expected argument type 'CFNotificationCallback!' (aka 'ImplicitlyUnwrappedOptional<@convention(c) (Optional, Optional, Optional, Optional, Optional) -> ()>')

Does anyone know what I'm doing wrong with the displayStatusChanged function? Any help, suggestions or link will be appreciated.

Thanks

Solution

According to the documentation:

the center parameter should be optional (i.e. missing ?),
for name you have CFString but the documentation says CFNotificationName?
and the CFDictionary should be optional (you're missing a ?),

Should fix your error if you match your parameters to the expected types.

func displayStatusChanged(center: CFNotificationCenter?, observer: UnsafeMutableRawPointer?, name: CFNotificationName?, object: UnsafeRawPointer?, userInfo: CFDictionary?) -> Void {

}