   /// Returns a new string made by deleting the last path
   /// component from the `String`, along with any final path
   /// separator.
-  @available(*, unavailable, message="Use stringByDeletingLastPathComponent on NSString instead.")
+  @available(*, unavailable, message="Use URLByDeletingLastPathComponent on NSURL instead.")
   public var stringByDeletingLastPathComponent: String {
     return _ns.stringByDeletingLastPathComponent
   }

  // - (const char *)fileSystemRepresentation

  /// Returns a file system-specific representation of the `String`.
  @available(*, unavailable, message="Use fileSystemRepresentation on NSString instead.")
  public func fileSystemRepresentation() -> [CChar] {
    return _persistCString(_ns.fileSystemRepresentation)!
  }


  /// Returns a new string made by appending to the `String` an
  /// extension separator followed by a given extension.
  @available(*, unavailable, message="Use URLByAppendingPathExtension on NSURL instead.")
  public func stringByAppendingPathExtension(ext: String) -> String? {
    // FIXME: This method can return nil in practice, for example when self is
    // an empty string.  OTOH, this is not documented, documentatios says that
