react-native-multiple-select | Simple multi-select component for react-native | Frontend Framework library

I can guess throughout the question that you are passing the hideTags props to the MultiSelect component i.e you are having inside the component <MultiSelect hideTags>. This hideTags was your problem because It does what it's name sounds, i.e it doesn't display the values you set in your FlatList or whatever component. If you want the values to be displayed then remove hideTags from inside the component and you should have your items displayed. Well you want also to customize the output of this library, it's colors and InputField style then head up to the root of your react native application, then go to node-module -> react-native-multiple-select -> Library there you will find the core file that you can customize at your leisure.

items prop is getting an undefined value because it's assigned this.items which doesn't exist in your class.

Change items={this.items} to items={this.sate.items} it makes more sense.

Another solution is to declare items array outside of the state.