Question

我已经在Swift for Lat / Long中编写了一个类，我希望将Location放在视图控制器上。我使用KVO作为MVC的一部分。我现在只是试验，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")
    }
}

但为什么不调用'observeValueForKeyPath函数？任何想法都会很棒。 LocationString是类顶部的动态var。 MyContext只是一个var int = 0

Answer 1

您正在将观察者附加到Class对象。假设你的'self'是LocationClass的实例并且具有'LocaionString'属性，它应该是

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

您首先分配值，将自我添加为观察者。在您注册观察该变量后，该值永远不会改变。

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

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

它的顺序应该不同：

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

SWIFT的KVO测试

2 个答案: