DAY 10

Classes

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At first, classes seem very similar to structs because we use them to create new data types with properties and methods. However, they introduce a new, important, and complex feature called inheritance – the ability to make one class build on the foundations of another.

This is a powerful feature, there’s no doubt about it, and there is no way to avoid using classes when you start building real iOS apps. But please remember to keep your code simple: just because a feature exists, it doesn’t mean you need to use it. As Martin Fowler wrote, “any fool can write code that a computer can understand, but good programmers write code that humans can understand.”

Today you have eight one-minute videos to watch, and you’ll meet things like method overrides, final classes, and deinitializers. Once you’ve watched each video and optionally gone through the extra reading, there’s a short test to help make sure you’ve understood what was taught.

1. Creating your own classes
   • Optional: Why does Swift have both classes and structs?
   • Test: Creating your own classes
2. Class inheritance
   • Optional: Why don’t Swift classes have a memberwise initializer?
   • Test: Class inheritance
3. Overriding methods
   • Optional: When would you want to override a method?
   • Test: Overriding methods
4. Final classes
   • Optional: Which classes should be declared as final?
   • Test: Final classes
5. Copying objects
   • Optional: Why do copies of a class share their data?
   • Test: Copying objects
6. Deinitializers
   • Optional: Why do classes have deinitializers and structs don’t?
   • Test: Deinitializers
7. Mutability
   • Optional: Why can variable properties in constant classes be changed?
   • Test: Mutability
8. Classes summary
   • Test: Classes

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