Adding readability for an if statement I often use.

EmptyOrNil.swift

protocol EmptyOrNil {
    var isEmpty: Bool { get }
}

extension Optional where Wrapped: EmptyOrNil {
    var isEmptyOrNil: Bool {
        return self?.isEmpty ?? true
    }
}

// Any type that has or can implement isEmpty
extension String: EmptyOrNil { }
extension Array: EmptyOrNil { }
extension Dictionary: EmptyOrNil where Key: Hashable { }
// ...

/* ------------------------------------------------------------------ */
// Example usage

// Before:

var optionalString: String? 

if optionalString?.isEmpty ?? true {
  // String doesnt contain anything
}

// After:

var optionalArray: Array<Any>?

if optionalArray.isEmptyOrNil {
  // Array doesnt contain anything
}


// You could even argue that 

guard !data.isEmptyOrNil else { return }

data!.doSomething

// is more readable than

guard let data = data, !data.isEmpty else { return }

data.doSomething