iOS10 UserDefaults file location/path?

You find your user default value in list file using below code

    var path: [AnyObject] = NSSearchPathForDirectoriesInDomains(.libraryDirectory, .userDomainMask, true) as [AnyObject]
    let folder: String = path[0] as! String
    NSLog("Your NSUserDefaults are stored in this folder: %@/Preferences", folder)

At this path you will find a plist file which is named by your <bundle identifier>.plist

You can also check it by typing print command in AppDelegate.swift file under

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {  
    print(NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true).last! as String)
}

When app builds it will print exact path in Debug area. You should then be able to locate .plist file which contains key-value pairs for data you stored.