Merge pull request kodecocodes#533 from remlostime/array2d-swift

[Swift 4] Update Array2D

Author: vincentngo

Array2D/Array2D.playground/Contents.swift

@@ -1,3 +1,8 @@
+// last checked with Xcode 9.0b4
+#if swift(>=4.0)
+print("Hello, Swift 4!")
+#endif
+
 /*
  Two-dimensional array with a fixed number of rows and columns.
  This is mostly handy for games that are played on a grid, such as chess.