在swift 3, Xcode 8.2:-检查电池状态水平

//Add observer
NotificationCenter.default.addObserver(self, selector: #selector(batteryStateDidChange), name: NSNotification.Name.UIDeviceBatteryStateDidChange, object: nil)


 //Fired when battery level changes

 func batteryStateDidChange(notification: NSNotification){
        //perform manipulation here
    }

使用NSNotificationCenter传递数据

也支持通过swift 3.0中的NotificationCentre和swift 2.0中的NSNotificationCenter进行数据传递。

Swift 2.0版本

使用userInfo传递信息，userInfo是一个可选的字典类型[NSObject: AnyObject]?

let imageDataDict:[String: UIImage] = ["image": image]

// Post a notification
 NSNotificationCenter.defaultCenter().postNotificationName(notificationName, object: nil, userInfo: imageDataDict)

// Register to receive notification in your class
NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(self.showSpinningWheel(_:)), name: notificationName, object: nil)

// handle notification
func showSpinningWheel(notification: NSNotification) {
  if let image = notification.userInfo?["image"] as? UIImage {
  // do something with your image   
  }
}

Swift 3.0版本

userInfo现在需要[AnyHashable:Any]?作为一个参数，我们在Swift中作为字典字面量提供

let imageDataDict:[String: UIImage] = ["image": image]

// post a notification
 NotificationCenter.default.post(name: NSNotification.Name(rawValue: "notificationName"), object: nil, userInfo: imageDataDict) 
// `default` is now a property, not a method call

// Register to receive notification in your class
NotificationCenter.default.addObserver(self, selector: #selector(self.showSpinningWheel(_:)), name: NSNotification.Name(rawValue: "notificationName"), object: nil)

// handle notification
func showSpinningWheel(_ notification: NSNotification) {

  if let image = notification.userInfo?["image"] as? UIImage {
  // do something with your image   
  }
}

使用NotificationCentre(swift 3.0)和NSNotificationCenter(swift 2.0)传递源数据

我能够做以下之一成功地使用选择器-没有注释任何@objc:

NSNotificationCenter.defaultCenter().addObserver(self,
    selector:"batteryLevelChanged:" as Selector,
    name:"UIDeviceBatteryLevelDidChangeNotification",
    object:nil)    

OR

let notificationSelector: Selector = "batteryLevelChanged:"

NSNotificationCenter.defaultCenter().addObserver(self,
    selector: notificationSelector,
    name:"UIDeviceBatteryLevelDidChangeNotification",
    object:nil)    

我的xcrun版本显示Swift 1.2，这适用于Xcode 6.4和Xcode 7 beta 2(我认为会使用Swift 2.0):

$xcrun swift --version

Apple Swift version 1.2 (swiftlang-602.0.53.1 clang-602.0.53)

Swift 5和Xcode 10.2:

NotificationCenter.default.addObserver(
            self,
            selector: #selector(batteryLevelDidChangeNotification),
            name: UIDevice.batteryLevelDidChangeNotification,
            object: nil)

Declare a notification name extension Notification.Name { static let purchaseDidFinish = Notification.Name("purchaseDidFinish") } You can add observer in two ways: Using Selector NotificationCenter.default.addObserver(self, selector: #selector(myFunction), name: .purchaseDidFinish, object: nil) @objc func myFunction(notification: Notification) { print(notification.object ?? "") //myObject print(notification.userInfo ?? "") //[AnyHashable("key"): "Value"] } or using block NotificationCenter.default.addObserver(forName: .purchaseDidFinish, object: nil, queue: nil) { [weak self] (notification) in guard let strongSelf = self else { return } strongSelf.myFunction(notification: notification) } func myFunction(notification: Notification) { print(notification.object ?? "") //myObject print(notification.userInfo ?? "") //[AnyHashable("key"): "Value"] } Post your notification NotificationCenter.default.post(name: .purchaseDidFinish, object: "myObject", userInfo: ["key": "Value"])

iOS 9和OS X 10.11。它不再需要一个 NSNotificationCenter观察者取消注册 收回。更多信息

对于基于块的实现，如果你想在块中使用self，你需要做一个弱-强舞蹈。更多信息

基于块的观察者需要删除更多信息

let center = NSNotificationCenter.defaultCenter()
center.removeObserver(self.localeChangeObserver)

创建一个objc函数，当通知被调用时执行该函数。

 @objc func reloadNotification(_ notification: Notification) {
        tblview.reloadData()
    }

在didload视图中添加通知观察者。

  NotificationCenter.default.addObserver(self, selector:#selector(reloadNotification(_:)), name: Notification.Name("reloadSideMenuDataNS"),object: nil) 

将通知发布到想要调用函数的位置。

 NotificationCenter.default.post(name: Notification.Name("reloadSideMenuDataNS"), object: nil) 

您可以删除您的通知在视图已消失下面。

 NotificationCenter.default.removeObserver(self, name: Notification.Name("reloadSideMenuDataNS"), object: nil)