DashboardDesignPage.ts

@IonicPage()
@Component({
  selector: 'page-dashboard-design',
  templateUrl: 'dashboard-design.html',
})
export class DashboardDesignPage {
  constructor(
    private userSessionManager: UserSessionManager
  }

  ionViewDidLoad() {
    this.userSessionManager.getFingerForLogin().then((result) => {
            let message = "You can change this later in Settings";
            let subTitle = "Enable fingerprint for login and authorizing transactions.";
            this.showFingerPrintAlert(subTitle, message);
          });
  }
}

IStorageProvider.ts

export interface IStorageProvider {
    get(key: string) : Promise<string>;
    set(key: string, value: string): boolean;
    clearKey(key: string) : boolean;
    clear():void;
}

StorageProvider.ts

import {Injectable} from '@angular/core';
import {Storage} from "@ionic/storage";
import {IStorageProvider} from "../interface/istorage-provider";

export const StorageProviderName = 'IStorageProvider';

export const StorageParameters = {
    HAS_FINGERPRINT: "hasFingerprint",
    
};

@Injectable()
export class StorageProvider implements IStorageProvider {
    keys: string[] = ['ExtraData', 'IsUserLoggedIn', 'Local_dp_part', 'LoggedInName', 'LoggedInNumber', 'refresh_token', 'token', 'UserPprogress', 'maybelater'];

    constructor(private storage: Storage) {
        // this.storage.keys().then((data) => {
        //     this.keys = data;
        // });
    }


    clear(): void {
        this.storage.clear();
    }


    clearKey(key: string): boolean {
        this.storage.remove(key);
        // if (this.giveKey().indexOf(key) > -1) {
        //     this.storage.remove(key).then((data) => {
        //         return true;
        //     }).catch((error) => {
        //         return false
        //     })
        // }
        // return false;
        return true;
    }


    async get(key: string): Promise<string> {
        let result;
        try {
            result = await this.storage.get(key);
        } catch (e) {
            throw e;
        }

        return result;
    }

    set(key: string, value: string): boolean {
        this.storage.set(key, value).then((onloadeddata) => {
            return true;
        }, () => {
        }).catch((error) => {
            //log
            return false;
        });

        return false;
    }

    setPromise(key: string, value: string) {
        return this.storage.set(key, value);
    }

}

UserSessionManager.ts

@Injectable()
export class UserSessionManager implements IUserSessionManager {
    constructor(private storageProvider: StorageProvider
    ) {
        this.storageProvider.get(StorageParameters.LOGGED_IN_USER).then((data) => {
            this.loggedInUser = JSON.parse(data) as User;
        });
    }

    async getFingerForLogin(): Promise<any> {
        return await this.storageProvider.get(StorageParameters.FINGERPRINT_FOR_LOGIN);
    }

}