type error null is not an object (evaluating 'ShareDialog.canShow') in React Native FBSDK

I have followed this GitHub URL to integrate Facebook sharing in my application.https://github.com/facebook/react-native-fbsdkHere is my code:

constructor(props){        super(props);        this.state={            shareLinkContent : {                contentType: 'link',                contentDescription: 'Facebook sharing is easy!',                contentUrl: 'https://cabbazar.com',            },    }shareLinkWithShareDialog() {    var tmp = this;    ShareDialog.canShow(tmp.state.shareLinkContent).then(      function(canShow) {        if (canShow) {          return ShareDialog.show(tmp.state.shareLinkContent);        }      }    ).then(      function(result) {        console.log('handle result: '+ result);      },      function(error) {        console.log('Share fail with error: '+ error);      }    );  }

But I am always getting an error in my simulator. Do I need to setup anything in for Xcode? I checked this url but it is not solving my problem. null is not an object (evaluating 'ShareDialog.canShow')

Please suggest.

Thanks