我想在观察者运行后或View消失时将其移除。这是代码，但有时当我想再次删除它时，观察者已经被删除。如何查看是否还在注册？overridefuncobserveValueForKeyPath(keyPath:String,ofObjectobject:AnyObject,change:[NSObject:AnyObject],context:UnsafeMutablePointer){if(!didOnce){if(keyPath=="myLocation"){location=mapView.myLocation.coordinate;self.mapView.animateToLoc

我想在观察者运行后或View消失时将其移除。这是代码，但有时当我想再次删除它时，观察者已经被删除。如何查看是否还在注册？overridefuncobserveValueForKeyPath(keyPath:String,ofObjectobject:AnyObject,change:[NSObject:AnyObject],context:UnsafeMutablePointer){if(!didOnce){if(keyPath=="myLocation"){location=mapView.myLocation.coordinate;self.mapView.animateToLoc