feat: add swift implementation to lcof problem: No.58.2 (#2949)

Author: klever34

lcof/面试题58 - II. 左旋转字符串/README.md

@@ -121,6 +121,19 @@ public class Solution {
 }
 ```
 
+#### Swift
+
+```swift
+class Solution {
+    func reverseLeftWords(_ s: String, _ n: Int) -> String {
+        let leftIndex = s.index(s.startIndex, offsetBy: n)
+        let rightPart = s[leftIndex..<s.endIndex]
+        let leftPart = s[s.startIndex..<leftIndex]
+        return String(rightPart) + String(leftPart)
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->

lcof/面试题58 - II. 左旋转字符串/Solution.swift

@@ -0,0 +1,8 @@
+class Solution {
+    func reverseLeftWords(_ s: String, _ n: Int) -> String {
+        let leftIndex = s.index(s.startIndex, offsetBy: n)
+        let rightPart = s[leftIndex..<s.endIndex]
+        let leftPart = s[s.startIndex..<leftIndex]
+        return String(rightPart) + String(leftPart)
+    }
+}