Added a ReadMe file.

Author: rzaccone

Trie/Trie/Trie.xcodeproj/project.pbxproj

@@ -17,6 +17,7 @@
 		EB798E2A1DFEF81400F0628D /* Trie.swift in Sources */ = {isa = PBXBuildFile; fileRef = EB798E281DFEF81400F0628D /* Trie.swift */; };
 		EB798E2C1DFEF90B00F0628D /* dictionary.txt in Resources */ = {isa = PBXBuildFile; fileRef = EB798E2B1DFEF90B00F0628D /* dictionary.txt */; };
 		EB798E2D1DFEF90B00F0628D /* dictionary.txt in Resources */ = {isa = PBXBuildFile; fileRef = EB798E2B1DFEF90B00F0628D /* dictionary.txt */; };
+		EB8369AD1E15C5710003A7F8 /* ReadMe.md in Sources */ = {isa = PBXBuildFile; fileRef = EB8369AC1E15C5710003A7F8 /* ReadMe.md */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXContainerItemProxy section */
@@ -51,6 +52,7 @@
 		EB798E1C1DFEF79900F0628D /* Info.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
 		EB798E281DFEF81400F0628D /* Trie.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Trie.swift; sourceTree = "<group>"; };
 		EB798E2B1DFEF90B00F0628D /* dictionary.txt */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text; path = dictionary.txt; sourceTree = "<group>"; };
+		EB8369AC1E15C5710003A7F8 /* ReadMe.md */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = net.daringfireball.markdown; path = ReadMe.md; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -101,6 +103,7 @@
 		EB798DFC1DFEF79900F0628D /* Trie */ = {
 			isa = PBXGroup;
 			children = (
+				EB8369AC1E15C5710003A7F8 /* ReadMe.md */,
 				EB798DFD1DFEF79900F0628D /* AppDelegate.swift */,
 				EB798DFF1DFEF79900F0628D /* ViewController.swift */,
 				EB798E011DFEF79900F0628D /* Assets.xcassets */,
@@ -267,6 +270,7 @@
 			files = (
 				EB798E291DFEF81400F0628D /* Trie.swift in Sources */,
 				EB798E001DFEF79900F0628D /* ViewController.swift in Sources */,
+				EB8369AD1E15C5710003A7F8 /* ReadMe.md in Sources */,
 				EB798DFE1DFEF79900F0628D /* AppDelegate.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;

Trie/Trie/Trie/ReadMe.md

@@ -0,0 +1,33 @@
+# Changes
+
+- Corrected a spelling error in a comment.
+
+- Got rid of the `get` syntax for a read only property as the coding guidelines suggest.
+
+- Changed several tests so that they are more Swift-like.  That is, they now feel like they are using the features of the language better.
+
+- Fixed a problem in the test method `testRemovePerformance`.  The `measure` method runs the block of code 10 times.  Previously, all words would get removed after the first run and the next 9 runs were very fast because there was nothing to do!  That is corrected now.
+
+- Made the `Trie` class a subclass of `NSObject` and had it conform to `NSCoding`.  Added a test to verify that this works.
+
+---
+
+I wasn't able to figure out how to recursively archive the trie.  Instead, I tried Kelvin's suggestion to use the `words` property to create an array of words in the trie, then archiving the array.
+
+There are a couple of nice aspects to this approach.
+
+- The `TrieNode` class can remain generic since it doesn't need to conform to `NSCoding`.
+
+- It doesn't require much new code.
+
+There are several downsides though.
+
+- The size of the archived words is three times the size of the original file of words!  Did I do this right?  The tests pass, so it seems correct.  I question whether archiving is worth the effort if the resulting archive is so much larger than the original file.
+
+- I would expect that archiving the trie would result in a file that was smaller than the original since a trie doesn't repeat leading character sequences when they are the same.
+
+- This requires that the trie get reconstructed when it is unarchived.
+
+- My gut tells me that it would be faster to archive and unarchive the trie itself, but I don't have any hard data to support this.
+
+I would like to see code that recursively archives the trie so we can compare the performance.