diff --git a/lcof/面试题48. 最长不含重复字符的子字符串/README.md b/lcof/面试题48. 最长不含重复字符的子字符串/README.md
index 4103da44fe..324c303bc6 100644
--- a/lcof/面试题48. 最长不含重复字符的子字符串/README.md	
+++ b/lcof/面试题48. 最长不含重复字符的子字符串/README.md	
@@ -220,6 +220,30 @@ public class Solution {
 }
 ```
 
+#### Swift
+
+```swift
+class Solution {
+    func lengthOfLongestSubstring(_ s: String) -> Int {
+        var ans = 0
+        var j = 0
+        var vis = Set<Character>()
+        let sArray = Array(s)
+
+        for i in 0..<sArray.count {
+            while vis.contains(sArray[i]) {
+                vis.remove(sArray[j])
+                j += 1
+            }
+            vis.insert(sArray[i])
+            ans = max(ans, i - j + 1)
+        }
+
+        return ans
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->
diff --git a/lcof/面试题48. 最长不含重复字符的子字符串/Solution.swift b/lcof/面试题48. 最长不含重复字符的子字符串/Solution.swift
new file mode 100644
index 0000000000..8656662fcf
--- /dev/null
+++ b/lcof/面试题48. 最长不含重复字符的子字符串/Solution.swift	
@@ -0,0 +1,19 @@
+class Solution {
+    func lengthOfLongestSubstring(_ s: String) -> Int {
+        var ans = 0
+        var j = 0
+        var vis = Set<Character>()
+        let sArray = Array(s)
+        
+        for i in 0..<sArray.count {
+            while vis.contains(sArray[i]) {
+                vis.remove(sArray[j])
+                j += 1
+            }
+            vis.insert(sArray[i])
+            ans = max(ans, i - j + 1)
+        }
+        
+        return ans
+    }
+}
\ No newline at end of file