我无法执行fittocoordinates方法

Question

<MapView

   style={ styles.map }
   initialRegion={{
     latitude: this.state.lat,
     longitude:this.state.long,
     latitudeDelta: 0.0922,
     longitudeDelta: 0.0421,
   }}

   region={{latitude: this.state.lat,
   longitude:this.state.long,
   latitudeDelta: 0.0922,
   longitudeDelta: 0.0421}}
   ref={(ref) => { this.mapRef = ref }}



>

<Polyline
        coordinates={[
            { latitude: this.state.picklat, longitude: this.state.picklong },
            { latitude: this.state.droplat, longitude: this.state.droplong }
        ]}
        strokeColor="#000" // fallback for when `strokeColors` is not supported by the map-provider
        strokeColors={[
            '#7F0000',
            '#00000000', // no color, creates a "long" gradient between the previous and next coordinate
            '#B24112',
            '#E5845C',
            '#238C23',
            '#7F0000'
        ]}
        strokeWidth={6}
    />

<Marker draggable
       coordinate={{latitude: this.state.picklat,
       longitude: this.state.picklong}}

         pinColor={"#56954A"}
      onDragEnd={(e)=>{this.setState({picklat:e.nativeEvent.coordinate.latitude,picklong:e.nativeEvent.coordinate.longitude},
        this.mapRef.fitToCoordinates([
          { latitude: this.state.picklat, longitude: this.state.picklong },
          { latitude: this.state.droplat, longitude: this.state.droplong }
        ], { edgePadding: { top: 10, right: 10, bottom: 10, left: 10 }, animated: true }))}}
        />

            <Marker draggable
            coordinate={{latitude: this.state.droplat,
            longitude: this.state.droplong}}
             pinColor={"#C5441B"}
           onDragEnd={(e)=>this.setState({droplat:e.nativeEvent.coordinate.latitude,droplong:e.nativeEvent.coordinate.longitude,lat:e.nativeEvent.coordinate.latitude,long:e.nativeEvent.coordinate.longitude})
          }
             />

当执行on dragEnd函数时，相机/视图中没有变化，看来fittocoordinates在代码中没有任何作用，但是我需要一些人来帮助解决这一问题，因为我一直在为此工作自从我是编程新手以来的15天