determine the CollectionType or String is nil or empty

NilOrEmpty.swift

public protocol Emptiable {
    var isEmpty: Bool { get }
}

extension String: Emptiable {}

extension Optional where T: Emptiable {
    public var isNilOrEmpty: Bool {
        guard let obj = self else { return true }
        return obj.isEmpty
    }
}

extension Optional where T: CollectionType {
    public var isNilOrEmpty: Bool {
        guard let obj = self else { return true }
        return obj.isEmpty
    }
}