Lab 6: Introduction to APIs - SoundCloud Player

Due

Wednesday, April 11 at 11:59 PM

Description

Two weeks before Spring Break, we covered some basics of networking in iOS. We will be using our knowledge of RESTful APIs to stream songs from SoundCloud. You will need to use their API reference to find the correct endpoints: https://developers.soundcloud.com/docs/api/reference

You will find reviewing material from that lecture to be useful (3/12).

Our goal in this assignment will be to create an app that plays tracks from a SoundCloud playlist. Additionally, this will serve as an exercise in working with APIs other than the Firebase API. By the end of this lab, you should be able to play, pause, skip and rewind songs on the app.

Instructions

Create a SoundCloud Player App

Files

• Track.swift - In the Model folder, this class will process the returned track attribute dictionary from the SoundClouds API, verify that it's streamable, & initalize a Track instance. You will be editing this file.
• SoundCloudAPI.swift - Also in the Model folder, this class only has the 'resolveAndLoadTracks(fromSoundCloudURL:)' function, which, as it gives away, loads tracks from SoundCloud and passes them to the Tracks class for processing. You will also be editing this file.
• PlayerViewController.swift - In the ViewControllers folder, this class is our ViewController which will update the UI when a user plays the song, clicks next or makes any request to our API. You will not be editing this class.
• The other files are just supporting files. The above three are the most important for this lab.

TODO

This is supposed to be a fast and easy lab so we can give you more time to work on your custom app and ask questions about it. If you try running the app right now, it will crash. To make it run, do the following in the following classes:

• SoundCloudAPI.swift
  • This is where you will do the chunk of the work. In the loadTracks function, we have created a URL session, however, we have not added any task to the session. Your job is to create a dataTask passing in the appropriate API endpoint URL (checkout the '/resolve' endpoint) using the passed in playlist URL, which will make an api call to SoundCloud and return the data we need. Then you will process the returned data from the url. In processing the data, you will create a an Array with objects of type 'Track', go through the returned data and get tracks (songs) that have been returned, initialize them as instances of the 'Track' class and append them to the Array you created earlier. Make sure you pass the values in your tracks Array to a completion before ending anything.
• Track.swift
  • For this class, you will be processing the data that is returned by the API. As such, it is recommended that you start working with the API class first. As was covered in lecture, the data that is returned by the API is in JSON format, which is structured as a Dictionary with Strings as keys and 'Any' as values. Your job is to get the song id, the name of the artist, and the title of the song. Refer to the instructions in the 'TODO' for the class.

Submission

• To get credit for this lab, make sure you get checked by a TA before the deadline.