Day12.md

Day 12 - HackingWithSwift - 100DaysOfSwiftUI Challenge

I call it(null referenes) a billion dollar mistake - Tony Hoare

Optionals

Today I learnt about:

• Handling missing data
• Unwrapping optionals with if let
• Unwraping optionals with guard let
• Force unwrapping
• Implicitly unwrapped optionals
• Nil coalescing
• Optional Chaining
• Optional try
• Failable initialisers
• Type casting

The summary of the entire day was:

• Optionals let us represent the absence of a value in a clear and unambiguous way.
• Swift won’t let us use optionals without unwrapping them, either using if let or using guard let.
• You can force unwrap optionals with an exclamation mark(!), but if you try to force unwrap nil your code will crash.
• Implicitly unwrapped optionals don’t have the safety checks of regular optionals.
• You can use nil coalescing to unwrap an optional and provide a default value if there was nothing inside.
• Optional chaining lets us write code to manipulate an optional, but if the optional turns out to be empty the code is ignored.
• You can use try? to convert a throwing function into an optional return value, or try! to crash if an error is thrown.
• If you need your initializer to fail when it’s given bad input, use init?() to make a failable initializer.
• You can use typecasting to convert one type of object to another.

That's all for the Day 12 of 100DaysOfSwiftUI!