DAY 11

Protocols and extensions

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Today you’re going to learn some truly Swifty functionality: protocols and protocol-oriented programming (POP).

POP does away with large, complex inheritance hierarchies, and replaces them with much smaller, simpler protocols that can be combined together. This really is the fulfillment of something Tony Hoare said many years ago: “inside every large program, there is a small program trying to get out.”

Today you have six one-minute videos to watch, and you’ll meet protocols, extensions, and the combination of those two: protocol extensions. Once you’ve watched each video and any optional extra reading you wanted, there’s a short test to help make sure you’ve understood what was taught.

1. Protocols
   • Optional: Why does Swift need protocols?
   • Test: Protocols
2. Protocol inheritance
   • Optional: When should we use protocol inheritance?
   • Test: Protocol inheritance
3. Extensions
   • Optional: When should you use extensions in Swift?
   • Test: Extensions
4. Protocol extensions
   • Optional: When are protocol extensions useful in Swift?
   • Test: Protocol extensions
5. Protocol-oriented programming
   • Optional: How is protocol-oriented programming different from object-oriented programming?
   • Test: Protocol-oriented programming
6. Protocols and extensions summary
   • Test: Protocols and extensions

That’s day 11 complete, so hopefully by now you know what to do: go and post about your progress online on Twitter, Facebook, Reddit, or whatever social media you like. You’re powered by POP now!

Need help? Tweet me @twostraws!

 

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