Calling a Android Native UI component method from React native Js code

Question

I have created a CustomView SignatureView.java which extends LinearLayout for capturing signature in Android Native.

And created SignatureCapturePackage.java and Signatu

Answer 1

I needed a solution that let me return values from my component instance method (Promises in my case). Using receiveCommand didn't allow me to do this.

I was able to solve this using UIManagerModule.addUIBlock, similar to https://stackoverflow.com/a/31936516/194065:

public class MyViewModule extends ReactContextBaseJavaModule {

    public static final String TAG = MyViewModule.class.getSimpleName();

    public MyViewModule(ReactApplicationContext reactContext) {
        super(reactContext);
    }

    @Override
    public String getName() {
        return "MyView";
    }

    @ReactMethod
    public void someMethod(final int viewId, final Promise promise) {
        withMyView(viewId, promise, new MyViewHandler() {
            @Override
            public void handle(MyView view) {
                String value = view.someMethod();
                promise.resolve(value)
            }
        });
    }

    private void withMyView(final int viewId, final Promise promise, final MyViewHandler handler) {
        UIManagerModule uiManager = getReactApplicationContext().getNativeModule(UIManagerModule.class);
        uiManager.addUIBlock(new UIBlock() {
            @Override
            public void execute(NativeViewHierarchyManager nativeViewHierarchyManager) {
                View view = nativeViewHierarchyManager.resolveView(viewId);
                if (view instanceof MyView) {
                    MyView myView = (MyView) view;
                    handler.handle(myView);
                }
                else {
                    Log.e(TAG, "Expected view to be instance of MyView, but found: " + view);
                    promise.reject("my_view", "Unexpected view type");
                }
            }
        });
    }


}

Usage:

import React, { Component } from 'react';
import { NativeModules, requireNativeComponent, findNodeHandle } from "react-native";
const MyViewFunctions = NativeModules.MyView;


class MyView extends Component {

    someMethod() {
        MyViewFunctions.someMethod(findNodeHandle(this.nativeCmp));
    }

    render() {
        return (
             this.nativeCmp = cmp}
                {...this.props}
            />
        );
}

const RCMyView = requireNativeComponent('RCMyView', MyView);

export default MyView;