Migrating Brute Force String Search to Swift3

Author: sendilkumarn

Brute-Force String Search/BruteForceStringSearch.playground/Contents.swift

@@ -1,16 +1,17 @@
 //: Playground - noun: a place where people can play
 
 extension String {
-  func indexOf(pattern: String) -> String.Index? {
-    for i in self.startIndex ..< self.endIndex {
+  func indexOf(_ pattern: String) -> String.Index? {
+    
+    for i in self.characters.indices {
       var j = i
       var found = true
-      for p in pattern.startIndex ..< pattern.endIndex {
-        if j == self.endIndex || self[j] != pattern[p] {
+      for p in pattern.characters.indices{
+        if j == self.characters.endIndex || self[j] != pattern[p] {
           found = false
           break
         } else {
-          j = j.successor()
+            j = self.characters.index(after: j)
         }
       }
       if found {

Brute-Force String Search/BruteForceStringSearch.playground/timeline.xctimeline

@@ -2,21 +2,21 @@
   Brute-force string search
 */
 extension String {
-  func indexOf(pattern: String) -> String.Index? {
-    for i in self.startIndex ..< self.endIndex {
-      var j = i
-      var found = true
-      for p in pattern.startIndex ..< pattern.endIndex {
-        if j == self.endIndex || self[j] != pattern[p] {
-          found = false
-          break
-        } else {
-          j = j.successor()
+  func indexOf(_ pattern: String) -> String.Index? {
+    for i in self.characters.indices {
+        var j = i
+        var found = true
+        for p in pattern.characters.indices{
+            if j == self.characters.endIndex || self[j] != pattern[p] {
+                found = false
+                break
+            } else {
+                j = self.characters.index(after: j)
+            }
+        }
+        if found {
+            return i
         }
-      }
-      if found {
-        return i
-      }
     }
     return nil
   }

Brute-Force String Search/BruteForceStringSearch.swift

@@ -28,21 +28,21 @@ Here is a brute-force solution:
 
 ```swift
 extension String {
-  func indexOf(pattern: String) -> String.Index? {
-    for i in self.startIndex ..< self.endIndex {
-      var j = i
-      var found = true
-      for p in pattern.startIndex ..< pattern.endIndex {
-        if j == self.endIndex || self[j] != pattern[p] {
-          found = false
-          break
-        } else {
-          j = j.successor()
+  func indexOf(_ pattern: String) -> String.Index? {
+    for i in self.characters.indices {
+        var j = i
+        var found = true
+        for p in pattern.characters.indices{
+            if j == self.characters.endIndex || self[j] != pattern[p] {
+                found = false
+                break
+            } else {
+                j = self.characters.index(after: j)
+            }
+        }
+        if found {
+            return i
         }
-      }
-      if found {
-        return i
-      }
     }
     return nil
   }