Swift - 判断设备方向

import UIKit

 
class ViewController: UIViewController {
     
    @IBOutlet weak var orientationLabel: UILabel!
     
    override func viewDidLoad() {
        super.viewDidLoad()
        
        //感知设备方向 - 开启监听设备方向
        UIDevice.currentDevice().beginGeneratingDeviceOrientationNotifications()
        //添加通知，监听设备方向改变
        NSNotificationCenter.defaultCenter().addObserver(self, selector: "receivedRotation",
            name: UIDeviceOrientationDidChangeNotification, object: nil)
         
        //关闭设备监听
        //UIDevice.currentDevice().endGeneratingDeviceOrientationNotifications()
    }
     
    //通知监听触发的方法
    func receivedRotation(){
        var device = UIDevice.currentDevice()
        switch device.orientation{
            case .Portrait:
                orientationLabel.text = "面向设备保持垂直，Home键位于下部"
            case .PortraitUpsideDown:
                orientationLabel.text = "面向设备保持垂直，Home键位于上部"
            case .LandscapeLeft:
                orientationLabel.text = "面向设备保持水平，Home键位于左侧"
            case .LandscapeRight:
                orientationLabel.text = "面向设备保持水平，Home键位于右侧"
            case .FaceUp:
                orientationLabel.text = "设备平放，Home键朝上"
            case .FaceDown:
                orientationLabel.text = "设备平放，Home键朝下"
            case .Unknown:
                orientationLabel.text = "方向未知"
            default:
                orientationLabel.text = "方向未知"
        }
    }
}