mapview如何自动缩放

Question

Answer: set delta to a smaller decimal number, eg 0.005

---

I am using <MapView> component, trying to make it default zoom in to a certain degree so that can see the street by default. I thought "Delta" is controlling how much we want to zoom, but i don`t see any different when i set different value.

any idea how can i have MapView default zoom in?

    region: {
        latitude: xxxx,
        longitude: xxxx,
        latitudeDelta: 0.4,
        longitudeDelta: 0.4,
        title: "Your Address"
    }

       <MapView style={styles.map}
                 region={this.state.region}
                 showsUserLocation={true}
                 annotations={[this.state.region]}>
        </MapView>

Answer 1

So with Apple's MKMapView class the zoom level is controlled indirectly. Rather than specifying how much you want to zoom on a point, you set the region you want to display. This requires a centre point, and a span - which can use the latitude and longitude deltas to the edge of the map. A smaller latitude and longitude delta will mean that you are zoomed in closer to the centre, and vice versa.

Here is the documentation.

https://developer.apple.com/library/mac/documentation/MapKit/Reference/MapKitDataTypesReference/index.html#//apple_ref/swift/struct/c:@SA@MKCoordinateRegion

The google maps API allows you to directly control the zoom level, but there are also libraries that will work for MKMapView.

Answer 2

I think that MapView in React Native automatically zooms to your location. If that is your case, and you don't want it to happen, you can comment this line in the react native file RCTMap.m in your react-native node module : _followUserLocation = showsUserLocation;