feat: add swift implementation to lcof2 problem: No.068

lcof2/剑指 Offer II 068. 查找插入位置/README.md

@@ -170,6 +170,26 @@ var searchInsert = function (nums, target) {
 };
 ```
 
+#### Swift
+
+```swift
+class Solution {
+    func searchInsert(_ nums: [Int], _ target: Int) -> Int {
+        var left = 0
+        var right = nums.count
+        while left < right {
+            let mid = (left + right) / 2
+            if nums[mid] >= target {
+                right = mid
+            } else {
+                left = mid + 1
+            }
+        }
+        return left
+    }
+}
+```
+
 <!-- tabs:end -->
 
 <!-- solution:end -->