@interface TreeNode : NSObject    @property NSNumber *value;    @property TreeNode *left;    @end      @implementation TreeNode      + (TreeNode *)mirrorTreeNode:(TreeNode *)node      if (node == nil) return nil;      TreeNode *mirrorNode = [TreeNode new];      mirrorNode.value = node.value;      mirrorNode.left = node.right;      mirrorNode.right = node.left;      return mirrorNode;    @end    
       
            以下是Objective-C实现二叉树镜像算法的示例代码：