Made improvements suggested by others. These changes cause things to be done in a more Swift-like manner. Also updated the project to Xcode 8.2.

Author: rzaccone

Trie/Trie/Trie.xcodeproj/project.pbxproj

@@ -193,7 +193,7 @@
 			isa = PBXProject;
 			attributes = {
 				LastSwiftUpdateCheck = 0810;
-				LastUpgradeCheck = 0810;
+				LastUpgradeCheck = 0820;
 				ORGANIZATIONNAME = "Rick Zaccone";
 				TargetAttributes = {
 					EB798DF91DFEF79900F0628D = {
@@ -333,6 +333,7 @@
 				CLANG_WARN_INFINITE_RECURSION = YES;
 				CLANG_WARN_INT_CONVERSION = YES;
 				CLANG_WARN_OBJC_ROOT_CLASS = YES_ERROR;
+				CLANG_WARN_SUSPICIOUS_MOVE = YES;
 				CLANG_WARN_SUSPICIOUS_MOVES = YES;
 				CLANG_WARN_UNREACHABLE_CODE = YES;
 				CLANG_WARN__DUPLICATE_METHOD_MATCH = YES;
@@ -382,6 +383,7 @@
 				CLANG_WARN_INFINITE_RECURSION = YES;
 				CLANG_WARN_INT_CONVERSION = YES;
 				CLANG_WARN_OBJC_ROOT_CLASS = YES_ERROR;
+				CLANG_WARN_SUSPICIOUS_MOVE = YES;
 				CLANG_WARN_SUSPICIOUS_MOVES = YES;
 				CLANG_WARN_UNREACHABLE_CODE = YES;
 				CLANG_WARN__DUPLICATE_METHOD_MATCH = YES;
@@ -508,6 +510,7 @@
 				EB798E211DFEF79900F0628D /* Release */,
 			);
 			defaultConfigurationIsVisible = 0;
+			defaultConfigurationName = Release;
 		};
 		EB798E221DFEF79900F0628D /* Build configuration list for PBXNativeTarget "TrieTests" */ = {
 			isa = XCConfigurationList;
@@ -516,6 +519,7 @@
 				EB798E241DFEF79900F0628D /* Release */,
 			);
 			defaultConfigurationIsVisible = 0;
+			defaultConfigurationName = Release;
 		};
 		EB798E251DFEF79900F0628D /* Build configuration list for PBXNativeTarget "TrieUITests" */ = {
 			isa = XCConfigurationList;
@@ -524,6 +528,7 @@
 				EB798E271DFEF79900F0628D /* Release */,
 			);
 			defaultConfigurationIsVisible = 0;
+			defaultConfigurationName = Release;
 		};
 /* End XCConfigurationList section */
 	};

Trie/Trie/Trie/Trie.swift

@@ -81,23 +81,19 @@ extension Trie {
             return
         }
         var currentNode = root
-        let charactersInWord = Array(word.lowercased().characters)
-        var index = 0
-        while index < charactersInWord.count {
-            let character = charactersInWord[index]
+        for character in word.lowercased().characters {
             if let childNode = currentNode.children[character] {
                 currentNode = childNode
             } else {
                 currentNode.add(value: character)
                 currentNode = currentNode.children[character]!
             }
-            index += 1
         }
         // Word already present?
         guard !currentNode.isTerminating else {
             return
         }
-        self.wordCount += 1
+        wordCount += 1
         currentNode.isTerminating = true
     }
 
@@ -110,13 +106,13 @@ extension Trie {
             return false
         }
         var currentNode = root
-        let charactersInWord = Array(word.lowercased().characters)
-        var index = 0
-        while index < charactersInWord.count, let childNode = currentNode.children[charactersInWord[index]] {
-            index += 1
+        for character in word.lowercased().characters {
+            guard let childNode = currentNode.children[character] else {
+                return false
+            }
             currentNode = childNode
         }
-        return index == charactersInWord.count && currentNode.isTerminating
+        return currentNode.isTerminating
     }
 
     /// Attempts to walk to the terminating node of a word.  The
@@ -127,20 +123,15 @@ extension Trie {
     /// search failed.
     private func findTerminalNodeOf(word: String) -> Node? {
         var currentNode = root
-        var charactersInWord = Array(word.lowercased().characters)
-        var index = 0
-        while index < charactersInWord.count {
-            let character = charactersInWord[index]
+        for character in word.lowercased().characters {
             guard let childNode = currentNode.children[character] else {
                 return nil
             }
             currentNode = childNode
-            index += 1
         }
         return currentNode.isTerminating ? currentNode : nil
     }
 
-
     /// Deletes a word from the trie by starting with the last letter
     /// and moving back, deleting nodes until either a non-leaf or a
     /// terminating node is found.
@@ -180,7 +171,7 @@ extension Trie {
         } else {
             terminalNode.isTerminating = false
         }
-        self.wordCount -= 1
+        wordCount -= 1
     }
 
     /// Returns an array of words in a subtrie of the trie
@@ -198,7 +189,7 @@ extension Trie {
         if rootNode.isTerminating {
             subtrieWords.append(previousLetters)
         }
-        for (_, childNode) in rootNode.children {
+        for childNode in rootNode.children.values {
             let childWords = wordsInSubtrie(rootNode: childNode, partialWord: previousLetters)
             subtrieWords += childWords
         }