DAY 12
Optionals
Null references – literally when a variable has no value – were invented by Tony Hoare way back in 1965. When asked about it in retrospect, he said “I call it my billion-dollar mistake” because they lead to so many problems.
This is the last day that you’ll be learning the fundamentals of Swift, and it’s devoted exclusively to Swift’s solution to null references, known as optionals. These are a really important language feature, but they can hurt your brain a little – don’t feel bad if you need to repeat some videos a few times.
Today you have 11 one-minute videos to watch, and you’ll meet unwrapping, optional chaining, typecasting, and more. Once you’ve watched each video and completed any optional extra reading you wanted, there’s a short test to help make sure you’ve understood what was taught.
- Handling missing data
- Optional: Why does Swift have optionals?
- Test: Handling missing data
- Unwrapping optionals
- Optional: Why does Swift make us unwrap optionals?
- Test: Unwrapping optionals
- Unwrapping with guard
- Optional: When to use guard let rather than if let
- Test: Unwrapping with guard
- Force unwrapping
- Optional: When should you force unwrap optionals in Swift?
- Test: Force unwrapping
- Implicitly unwrapped optionals
- Nil coalescing
- Optional: When should you use nil coalescing in Swift?
- Test: Nil coalescing
- Optional chaining
- Optional: Why is optional chaining so important?
- Test: Optional chaining
- Optional try
- Optional: When should you use optional try?
- Test: Optional try
- Failable initializers
- Optional: Why would you want a failable initializer?
- Test: Failable initializers
- Typecasting
- Optional: When is type casting useful in Swift?
- Test: Typecasting
- Optionals summary
- Test: Optionals
Have some questions about optionals?
Hit Send below to start a virtual conversation with me.
Need help? Tweet me @twostraws!
SPONSORED Play is the first native iOS design tool created for designers and engineers. You can install Play for iOS and iPad today and sign up to check out the Beta of our macOS app with SwiftUI code export. We're also hiring engineers!
Sponsor Hacking with Swift and reach the world's largest Swift community!
100 Days of Swift
The 100 Days of Swift is a free collection of videos, tutorials, tests, and more to help you learn Swift faster. Click here to learn more, or watch the video below.
