Optionals.md

Optionals

When do we use them?

Optionals are used when something is not known at the time of initialization, when an API can fail, or when the absence of a value provides additional meaning.

Key Considerations

• Evaluate if you need an optional value, and avoid them if possible.
• Do not make Bools optional.
  • A tri-state Bool can be represented in a more structured way, such as an enum with three well-named cases.
• Avoid making Arrays optional.
  • Only do this if it provides meaning beyond it just being empty.
• System APIs may require us to use optional values since they return optional values.
  • URLs created using init?(string:) are a common example.
• weak properties must be optional by definition because they can become nil.

Dealing with Optionals

• Always handle unwrapping optionals safely.
• We prefer conditional binding (if let) over flatMap.
• If a function requires an optional value to have a value, we opt to bind with guard statements and return early.

Reference Docs

• The Basics — The Swift Programming Language