Let's say you need to build an app and you face the following design problem: you need a picture editor, a piece of code that allows the user of your awesome app to select a picture from the photo library, rotate it, re-size it, apply some image filters and crop the result. You have two options, come up with your own code or use somebody else's code. But how do you find a library that performs what you want? How do you keep this library updated once the developers release a new version? What if that library uses other libraries and you need to install these dependencies too? Well, CocoaPods let's you do all these tasks and it is very easy to use. CocoaPods is a dependency manager for Swift and Objective-C Cocoa projects. It has over 28 thousand libraries and is used in over 1.7 million apps. CocoaPods can help you scale your projects elegantly. In this practical session I will explain how to use CocoaPods to help you build your apps. We will learn how to manage the external libraries, go over the best practices, dos and don'ts, and explore other alternatives to manage your app external dependencies.

1. Manage your external
libraries with CocoaPods
Juan Catalan
jcatalan007@gmail.com

2. About me
• Senior iOS developer working at Actsoft, Inc, in
sunny Tampa, FL, USA
• Started iOS development in 2009
• 20+ apps in the App Store
• Objective C veteran, Swift enthusiast

3. Agenda
• What is CocoaPods and why you should use it
• CocoaPods.org
• Demo: Setting up and using CocoaPods
• Alternatives to CocoaPods

4. What is CocoaPods?
• CocoaPods is a dependency manager for Swift and
Objective-C Cocoa projects. It has over 30 thousand
libraries and is used in over 1.9 million apps. CocoaPods
can help you scale your projects elegantly.
• A dependency manager is a tool that manages the third
party frameworks and packages you include in your Xcode
project in order to build your app.
• A framework is a reusable set of libraries or classes for a
software system
https://cocoapods.org

5. What is CocoaPods?
• Apple includes many frameworks as part of the
iOS SDK, however some times you need to
implement a functionality that is not included in
the iOS SDK.
• Instead of investing a lot of time implementing a
feature by yourself, you could use a third party
library to implement the desired functionality.

6. Why CocoaPods?
• Using third party libraries without a dependency manager
poses some challenges:
• Updating a library to a newer version could be problematic,
specially if it depends on another library.
• Modifying a library could introduce incompatible changes
with future versions of that library
• It’s difficult to keep track of each version of a library used in
your code
• Discovering new library is difficult without a centralized
location to see all the available libraries.

7. Why CocoaPods?
• Cocapods provides a solution to the problems mentioned
before:
• Fetches the code for the libraries and includes it in your
Xcode project in an automated way
• Keeps track of the version of the library and its updates when
needed
• Keeps track and resolves dependencies between the different
libraries used
• Provides a centralized repository with more that 30,000
libraries

8. Demo: cocoapods.org

9. CocoaPods.org
• Homepage:
• Search
• Quick installation and getting started
• Create a pod

10. CocoaPods.org
• Search:
• ImagePicker with multiple images
• Facebook
• Realm, Firebase
• Zip, ISO8601

11. CocoaPods.org
• Guides
• Blog
• CocoaDocs: cocoadocs.org
• AFNetworking
• Facebook-iOS-SDK / FacebookCore

12. Demo: NASA Images
sample app

13. NASA Images
• Downloads pictures from the Astronomy Picture of
the Day website (https://apod.nasa.gov) and
shows the pictures in a scrolling list view.
• Uses NASA Open API web services
• Uses best practices: parallel downloads, smooth
UI scrolling while downloads are in progress,
provides a mechanism to refresh the UI, etc.

14. NASA Images

15. NASA Images

16. NASA Images
• Downloads pictures from the Astronomy Picture of
the Day website (https://apod.nasa.gov) and
shows the pictures in a scrolling table view.
• Uses NASA Open API web services
• Uses best practices: parallel downloads, smooth
UI scrolling while downloads are in progress,
provides a mechanism to refresh the UI, etc.
Networking
JSON
Image Downloader

17. NASA Images
UITableView
UILabel
UIImageViewUIRefreshControl
UITextView
Progress Indicator

18. Demo: NASA Images
sample app

19. NASA Images
• sudo gem install cocoapods | pod setup --verbose
• pod init -> show file system
• modify pod file
• pod install -> Show terminal, show file system
• Show Podfile.lock and explain
• Show Pods directory and explain
• close Xcode project and open Xcode workspace
• Show Xcode project file navigator
• Show podfile
• Add podfile to project (drag and drop, uncheck copy if needed, Ruby script)
• Import statements in project source files

20. NASA Images
• go to https://api.nasa.gov/api.html#apod
• show specifications for the endpoint
• show example JSON returned (use browser)
• show code for Alamofire GET request
• show code using SwiftyJSON
• show code for HUD
• show code for Image Downloader

21. Pod file examples
• podfile and podfile.lock

22. Best practices
• Under source control:
• podfile
• podfile.lock
• .xcworkspace
• PODS directory - controversy
• Pod install vs Pod update - be in control

23. Alternatives to CocoaPods
• Carthage
• A decentralized dependency manager
• Swift Package Manager
• Only available in Mac OS and Linux apps

24. Thanks!
• Source code
https://github.com/jcatalan007/cocoapods-talk
• Slides
https://www.slideshare.net/jcatalan007/manage-
your-external-libraries-with-cocoapods