# Changelog

  • Fixed outdated api to retrieve service

# Introduction

One of the core steps of building a mobile application is sourcing data from different external sources. In practice, there are different options

  • REST endpoints (JSON over HTTP(S) )

  • MQTT endpoints (Use of MQTT messaging technology)

  • SOAP endpoints

  • proprietary endpoints

We describe some of the options in the following chapter

# REST endpoint consumption

Consuming a REST http(s) endpoint is one of the most common scenarios. In this chapter, using the **REST Service consumption wizard**, we will show how to

  • Consume a REST HTTPS endpoint

  • Automatically parse JSON and generate Swift classes from it

  • Automatically generate client Swift code to call the endpoint

  • Call the REST Service and handle any kind of exception

In this example, we use a sample REST service that returns a list of dummy banking accounts. You can use it too, it's a simple REST endpoint on AWS:

`https://aq5dv0hhp7.execute-api.us-west-2.amazonaws.com/prod/accounts`

Executing this with **username**=_demo_ and **password**=_demo_ returns a JSON document



So lets consume the same service in our mobile app:

# Step 1 - Create the data service

One data service consists of many HTTP methods, i.e. different REST endpoints that you can call. We add one GET methods first:

  1. Select New | Service

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  1. Give it a name of **banking**. This is name for all banking related REST endpoints

  2. As Request URL, specify the first REST endpoint that you want to consume

    • by convention, we combine the HTTP verb with the last part of the URL

    • so here, the Swift method that is generated becomes **getAccounts**

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  1. Now click on "Invoke Remote Request" to execute the request

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  1. Now click on **Invoke Remote Request** to execute the request The username/password is demo/demo.

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  1. Click on **Next** as we will not configure request parameter

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  1. Review the raw contents

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  1. Review the model that has been generated

  • Use the type column to redefine types

  • Sometimes, for instance, you want to use a String type There is no need to do anything here, just click **Finish**

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  1. Finally, press finish to create the structures This will take 5-10 seconds. After that the Swift structures have been created that reflect this JSON structure we retrieved from the REST endpoint:

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# Step 2 - Invoke the REST service

Now, all we need to do is to invoke the data service. Here a short snippet of code to invoke it.



When running it in the simulator, the accounts name are printed in the console

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# Current limitations

  1. We don't support JSON arrays, i.e. JSON documents beginning with [ at the moment. As a workaround, parse the JSON document manually or change the JSON data structure you retrieve.