[IOS] How to get the table name from AWS DynamoDB

Introduction

I decided to develop an application linked with AWS in the project, but unexpectedly there were few articles to refer to, so I had a hard time, so I summarized the procedure. This time I will try to get the table name from DynamoDB.

Development environment

• Swift 5
• Xcode 12
• aws-amplify/aws-sdk-ios
• cocoapods

Introduction of Cocoapods

Follow the README procedure in aws-amplify/aws-sdk-ios.

First, install cocoapods.

Terminal

$ gem install cocoapods
$ pod setup

Pod init directly under the project directory

Terminal

$ pod init

Since the podfile has been created, I will describe the AWS service to use

Podfile

target 'aws-sdk' do
  # Comment the next line if you don't want to use dynamic frameworks
  use_frameworks!

  pod 'AWSDynamoDB'
end

After installing the pod, reopen Xcode with xed ..

Terminal

$ pod install --repo-uodate
$ xed .

Settings for connecting to AWS

You need to authenticate with AWS to connect to AWS. As far as I have investigated, there are the following two types.

1. Authentication using Coginito (this is written in the README of aws-sdk)
2. Authentication using AWS access-key and secret e-key

I tried both, but Cognito's authentication was cumbersome to set up, so I decided to authenticate with method 2. Please refer to the following for issuing the Key.

How do I create an AWS access key? Create Qiita AWS Access Key

Authentication is set in AppDelegate.swift.

AppDelegate.swift

import UIKit
import AWSCore

@main
class AppDelegate: UIResponder, UIApplicationDelegate {

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {

　　　　　//Add the following
        let accessKey = Constans.accessKey
        let secretKey = Constans.secretKey
        let provider = AWSStaticCredentialsProvider(accessKey: accessKey, secretKey: secretKey)

        let configuration = AWSServiceConfiguration(
            region: AWSRegionType.APNortheast1,  //Please change the region as appropriate
            credentialsProvider: provider)

        AWSServiceManager.default().defaultServiceConfiguration = configuration

        return true
    }
}

The management of the accessKey and secretKey of AWSStaticCredentialsProvider (accessKey: accessKey, secretKey: secretKey) is left to you individually. (Please be careful not to publish it.)

In my case, I managed it with cocoapods-keys in the case, but this time I created a constant class simply. The created file is set to .gitignore so that it will not be pushed. orta/cocoapods-keys

Constants.swift

import Foundation

class Constans {
    static let accessKey = "AWS access-key"
    static let secretKey = "AWS secret-key"
}

Get table name from AWS DynamoDB

ViewController.swift

import UIKit
import AWSDynamoDB

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        fetchDynamoDBTableName()
    }
    
    private func fetchDynamoDBTableName() {
        let dynamoDB = AWSDynamoDB.default()
        let listTableInput = AWSDynamoDBListTablesInput()
        dynamoDB.listTables(listTableInput!).continueWith { (task:AWSTask<AWSDynamoDBListTablesOutput>) -> Any? in
            if let error = task.error as? NSError {
            print("Error occurred: \(error)")
                return nil
            }

            let listTablesOutput = task.result

            for tableName in listTablesOutput!.tableNames! {
                print("\(tableName)")
            }

            return nil
        }
    }
}

When you build with this, you should see the table name that exists in DynamoDB on the console. If there are multiple tables, multiple are displayed. I described the method in ViewController, but since ViewController becomes Fat, I think it is better to create a class for DynamoDM.

This repository

For your reference. https://github.com/shungo0525/aws-sdk

in conclusion

This time I only get the table name of DynamoDB, but I would like to post about the acquisition of DB data and the cooperation with S3.