diff --git a/swift/0374-guess-number-higher-or-lower.swift b/swift/0374-guess-number-higher-or-lower.swift
new file mode 100644
index 000000000..d461f6ce1
--- /dev/null
+++ b/swift/0374-guess-number-higher-or-lower.swift
@@ -0,0 +1,23 @@
+// Time: O(log n)
+// Space: O(1)
+class Solution : GuessGame {
+    func guessNumber(_ n: Int) -> Int {
+        // return a num btw 1,..,n
+        var low = 1
+        var high = n
+
+        while true {
+            let mid = low + (high - low) / 2
+            let myGuess = guess(mid)
+            if myGuess == 1 {
+                low = mid + 1
+            }
+            else if myGuess == -1 {
+                high = mid - 1
+            }
+            else {
+                return mid
+            }
+        }
+    }
+}
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