SWIFT中的KVO测试

Question

我已经在Swift中为纬度/经度编写了一个类，并且希望将Location放置在视图控制器上。 我正在将KVO用作MVC的一部分。 我目前正在试用，但为什么不

 func locationManager(manager: CLLocationManager!, didUpdateLocations locations: [AnyObject]!) {

    let location = locations.last as! CLLocation
    let geocoder = CLGeocoder()
    geocoder.reverseGeocodeLocation(location, completionHandler: { (placemarks, e) -> Void in
        if let error = e {
            println("Error:  (e.localizedDescription)")
        } else {
            let placemark = placemarks.last as! CLPlacemark
            LocationClass.addObserver(self, forKeyPath: "LocationString", options: .New, context: &self.myContext)
            self.LocationManager.stopUpdatingLocation()
            self.LocationString = "\(placemark.subLocality), \(placemark.locality)"
        }
    })



}


override func observeValueForKeyPath(keyPath: String, ofObject object: AnyObject, change: [NSObject: AnyObject], context: UnsafeMutablePointer<Void>) {
            println("Things have changed")
    }
}

但是为什么不'observeValueForKeyPath函数被调用？ 任何想法都很棒。 LocationString是类顶部的动态变量。 MyContext只是一个var int = 0

Answer 1

您正在将观察者附加到Class对象。 假设您的“自我”是LocationClass的实例，并且具有“ LocaionString”属性，则应为

self.addObserver(self, forKeyPath: "LocationString", options: .New, context: &self.myContext)

并且不要忘记附加“动态”修饰符

Answer 2

首先，您要分配值，将自身添加为观察者。 注册观察该变量后，该值永远不会更改。

self.LocationString = "\(placemark.subLocality), \(placemark.locality)"
                    //println(LocationString)

LocationClass.addObserver(self, forKeyPath: "LocationString", options: .New, context: &self.myContext)/

它应该以不同的顺序：

LocationClass.addObserver(self, forKeyPath: "LocationString", options: .New, context: &self.myContext)/
self.LocationString = "\(placemark.subLocality), \(placemark.locality)"
                    //println(LocationString)