Browse Questions
  • A retain cycle occurs when two objects hold strong references to each other, preventing ARC from deallocating either.
  • Combine subscriptions and NotificationCenter block observers cause leaks when the observation token is stored on self while the callback closure captures self strongly.
  • Clean Architecture organises code into concentric layers where dependencies only point inward.
  • An Optional is a type that can hold either a value or nil.

Answer: An Optional is a type that can hold either a value or nil. It's Swift's way of expressing the absence of a value safely, avoiding null pointer crashes common in Objective-C.

Code Example:

var name: String? = "Alice"  // Optional String
var age: Int? = nil          // no value

// Unwrapping safely
if let name = name {
    print("Hello, \(name)")
}

// Nil coalescing — provide a default
let displayName = name ?? "Guest"

// Optional chaining — safely access properties
let count = name?.count  // returns Int? not Int

Key Points:

  • String? is shorthand for Optional<String>
  • Never force unwrap (!) unless you are 100% certain it has a value
  • Prefer if let, guard let, or ?? for safe unwrapping

Further reading