problems(swift): add “867. Transpose Matrix”

Signed-off-by: Matej Focko <mfocko@redhat.com>

problems/swift/transpose-matrix.swift

@@ -0,0 +1,16 @@
+class Solution {
+    func transpose(_ matrix: [[Int]]) -> [[Int]] {
+        var m = Array(
+            repeating: Array(repeating: 0, count: matrix.count),
+            count: matrix[0].count
+        )
+
+        for y in 0..<matrix.count {
+            for x in 0..<matrix[y].count {
+                m[x][y] = matrix[y][x]
+            }
+        }
+
+        return m
+    }
+}