protextension.swift

public protocol Occupiable {
  var isEmpty: Bool { get }
  var isNotEmpty: Bool { get }
}

public extension Occupiable {
  public var isNotEmpty: Bool { return !isEmpty }
}

extension CollectionType where Self : Occupiable { }
extension String: Occupiable { }

public extension Optional where Wrapped : Occupiable {
  var isNilOrEmpty: Bool {
    return self?.isEmpty ?? false
  }
  var isNotNilOrEmpty: Bool {
    return !isNilOrEmpty
  }
}

let ar = [1, 2, 3, 4, 5]

ar.isNotEmpty

let optAr: [Int]? = [1, 2, 3, 4, 5]

optAr.isNilOrEmpty