What is the difference between `Debug` and `Release` build configurations?

Polymorphism lets code work with values of different underlying types through a single shared interface.
Secure Comparator is a zero-knowledge protocol that lets two parties confirm they hold the same secret without either side transmitting it, or leaking anything usable when the secrets differ.
Build configurations control compiler optimisations and flags.
Use Secure Message when two parties with separate key pairs exchange data, and Secure Cell when a single party encrypts data for itself.

Answer: Build configurations control compiler optimisations and flags. Debug is for development; Release is what ships to users.

	Debug	Release
Optimisation	None (`-Onone`)	Full (`-O`)
Debug symbols	✅ Included	❌ Stripped
Assertions	Active	Disabled
`#if DEBUG`	`true`	`false`
Build speed	Fast	Slow
Runtime speed	Slow	Fast

Code Example:

// Code only runs in Debug builds
#if DEBUG
func printDebugInfo() {
    print("User: \(currentUser)")
    print("API: \(apiBaseURL)")
}
#endif

// Assertion — removed in Release builds, no performance impact in production
assert(!items.isEmpty, "Items should never be empty here")

// Fatal error — always present (use for programmer errors)
guard let url = URL(string: urlString) else {
    fatalError("Invalid hardcoded URL — developer error")
}