Convenience extension on Optionals to return true or false if the collection is not empty and has elements

Optional+Extensions.swift

var userPreferences: [String]? = [""]

/// Type safe method to check if collection is nil and if not if it has values
func nilOrEmptyCollection<Collection where Collection: CollectionType>(collection: Collection?) -> Bool {
	guard let collection = collection else { return true }
	return collection.isEmpty
}

/// Extension on Options with constraint to collection type
extension Optional where Wrapped: CollectionType {
	func nilOrEmptyCollection() -> Bool {
		guard let value = self else { return true }
		return value.isEmpty
	}

	func hasElements() -> Bool {
		return !nilOrEmptyCollection()
	}
}

/// Version 1
if !nilOrEmptyCollection(userPreferences) {
	print("Do something with collection")
}

/// Version 2
if let values = userPreferences where !values.isEmpty {
	print("Do something with collection")
}

/// Version 3
var isEmpty = userPreferences?.isEmpty ?? true
if !isEmpty {
	print("Do something with collection")
}

/// Version 4
if userPreferences.hasElements() {
	print("Do something with collection")
}