这是发布通知的方法。它实际上是返回日期选择器的结果(日期)。

@IBAction func dateOfBirthAction(sender: AnyObject) {

    println("Date: \(dateOfBirthPicker.date)")

    var selectedDateDictionary = [dateOfBirthPicker.date,"dateOfBirth"]

    NSNotificationCenter.defaultCenter().postNotificationName("dateOfBirth",object: nil,userInfo: [NSObject():selectedDateDictionary])

}

这是通知观察员：

override func viewDidLoad() {
    super.viewDidLoad()

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

}

func dateOfBirth(notification: NSNotification) {

    println("userInfo: \(notification.userInfo)")

    let returnedDateOfBirth = notification.userInfo!["dateOfBirth"] as NSString
    println("returnedDateOfBirth: \(returnedDateOfBirth)")

    playerInformationDateOfBirthLabel.text  = returnedDateOfBirth
}

我在线上出现以下错误let returnDateOfBirth：String = notification.userInfo [“dateOfBirth”]

userInfo: Optional([<NSObject: 0x7fb15a44a880>: <_TtCSs23_ContiguousArrayStorage00007FB15A4D4380 0x7fb15a4206a0>(
2014-09-18 12:07:07 +0000,dateOfBirth
)
])
fatal error: unexpectedly found nil while unwrapping an Optional value

完整解决方案

@IBAction func dateOfBirthAction(sender: AnyObject) {

    var selectedDateDictionary = ["birthDate" : dateOfBirthPicker.date]

    NSNotificationCenter.defaultCenter().postNotificationName("foundABirthDate",userInfo:selectedDateDictionary)
}

override func viewDidLoad() {
    super.viewDidLoad()

    NSNotificationCenter.defaultCenter().addObserver(self,name: "foundABirthDate",object: nil)

}

func dateOfBirth(notification: NSNotification) {

    let playerBirthDate = notification.userInfo!["birthDate"] as NSDate

    var dateFormatter: NSDateFormatter = NSDateFormatter()

    //Specifies a long style,typically with full text,such as “November 23,1937”.
    dateFormatter.dateStyle = NSDateFormatterStyle.LongStyle

    let dateConvertedToString: String = dateFormatter.stringFromDate(playerBirthDate)

    playerInformationDateOfBirthLabel.text  = dateConvertedToString
}