toast.js

render() {
    return (
        <View>
            <Button title={'Press me'} onPress={()=>{
                    this.toast.show('hello world!',2000);
                }}/>
            <Toast
                ref={(toast) => this.toast = toast}
                style={{backgroundColor:'red'}}
                position='top'
                positionValue={200}
                fadeInDuration={750}
                fadeOutDuration={1000}
                opacity={0.8}
                textStyle={{color:'red'}}
            />
        </View>
    );
}