我希望在观察者运行后或视图消失时将其移除。这是代码,但有时当我想再次删除它时,观察者已被删除。如何检查它是否仍然注册?
override func observeValueForKeyPath(keyPath: String, ofObject object: AnyObject, change: [NSObject : AnyObject], context: UnsafeMutablePointer<Void>) {
if(!didOnce){
if(keyPath == "myLocation"){
location = mapView.myLocation.coordinate;
self.mapView.animateToLocation(self.location!);
self.mapView.animateToZoom(15);
didOnce = true;
self.mapView.removeObserver(self, forKeyPath: "myLocation");
}
}
}
override func viewDidAppear(animated: Bool) {
didOnce = false;
}
override func viewWillDisappear(animated: Bool) {
if(!didOnce){
self.mapView.removeObserver(self, forKeyPath: "myLocation");
didOnce = true;
}
}