Question

    func shouldirotate(){

    var whichwaywhere: String {

        if UIDevice.currentDevice().orientation == UIDeviceOrientation.LandscapeLeft {
            return "left"
        }
        if UIDevice.currentDevice().orientation == UIDeviceOrientation.LandscapeRight {
            return "right"
        }
        if UIDevice.currentDevice().orientation == UIDeviceOrientation.PortraitUpsideDown {
            return "down"
        }
        return "I don't Care"
    }
    println(whichwaywhere)
}

当我创建一个连续检查自身的函数时，（将shouldirotate附加到NSTimer）我可以检查方向。当UIDeviceOrientationDidChangeNotification激活时，我怎么能告诉函数运行？

要让UIDeviceOrientationDidChangeNotification运行，我有一个变量：

var rotatenote: Bool = UIDevice.currentDevice().generatesDeviceOrientationNotifications

并且在ViewDidLoad覆盖中我有：

override func viewDidLoad() {
    UIDevice.currentDevice().beginGeneratingDeviceOrientationNotifications()
    rotatenote = true
}

这是使用和声明此属性的正确方法吗？如何让函数运行DeviceOrientationNotification？

P.S。：我在ViewDidLoad中有一个rotatenote = true，因为如果我试着像往常一样将它附加到变量声明中，它会说＆＃34;不能分配给这个表达式的结果。＆＃34;见下文

var rotatenote: Bool = UIDevice.currentDevice().generatesDeviceOrientationNotifications = true

Answer 1

有几种方法可以做到这一点。不确定你担心什么操作系统，但在iOS 8中你有两个简单的选择。您可以注册

的观察者

UIDeviceOrientationDidChangeNotification

或者您可以覆盖

func viewWillTransitionToSize(size: CGSize, withTransitionCoordinator coordinator: UIViewControllerTransitionCoordinator)

你应该不需要

UIDevice.currentDevice().beginGeneratingDeviceOrientationNotifications()

所以要么在viewDidLoad中添加：

NSNotificationCenter.defaultCenter().addObserver(self, selector: "functionThatYouWantTriggeredOnRotation", name:
        UIDeviceOrientationDidChangeNotification, object: nil)

你有一个函数functionThatYouWantTriggeredOnRotation进行计算......

或者你可以只为viewWillTransition提供覆盖，而不必为UIDeviceOrientationDidChangeNotification

添加观察者

override func viewWillTransitionToSize(size: CGSize,
      withTransitionCoordinator coordinator: UIViewControllerTransitionCoordinator)
{
    if UIDevice.currentDevice().orientation.isLandscape {
            //do your thing
        }
}

设备轮换通知无法正常工作iOS Swift

1 个答案: