refactor: use Package.swift to define executable task

codes/swift/utils/TreeNode.swift

@@ -0,0 +1,17 @@
+/*
+ * File: TreeNode.swift
+ * Created Time: 2023-01-02
+ * Author: nuomi1 (nuomi1@qq.com)
+ */
+
+public class TreeNode {
+    public var val: Int // 结点值
+    public var height: Int // 结点高度
+    public var left: TreeNode? // 左子结点引用
+    public var right: TreeNode? // 右子结点引用
+
+    public init(x: Int) {
+        val = x
+        height = 0
+    }
+}