Memory leaks iOS UITableItem设置FinishedSelectedImage:With FinishedSelectedImage:内存泄漏？

我有一个关于Uitabritem的内存泄漏情况。我的应用程序有一个带有自定义图片的TabBarController。这是我放在图形文件上的代码

UIImage *selectedImage0 = [UIImage imageNamed:@"A-click.png"];
UIImage *unselectedImage0 = [UIImage imageNamed:@"A.png"];

UIImage *selectedImage1 = [UIImage imageNamed:@"B-click.png"];
UIImage *unselectedImage1 = [UIImage imageNamed:@"B.png"];

UITabBar *tabBar = self.mytabbarcontroller.tabBar;
UITabBarItem *item0 = [tabBar.items objectAtIndex:0];
UITabBarItem *item1 = [tabBar.items objectAtIndex:1];

[item0 setFinishedSelectedImage:selectedImage0 withFinishedUnselectedImage:unselectedImage0];
[item1 setFinishedSelectedImage:selectedImage1 withFinishedUnselectedImage:unselectedImage1];

而且它工作得非常好！！！ 然而，当我使用Instruments工具检查内存泄漏时，它显示有来自的泄漏

[item0 setFinishedSelectedImage:selectedImage0 withFinishedUnselectedImage:unselectedImage0];
[item1 setFinishedSelectedImage:selectedImage1 withFinishedUnselectedImage:unselectedImage1];

如果我在不使用setFinishedSelecteImage的情况下注释这两行，就不会出现泄漏。我觉得这很奇怪，对我来说毫无意义。已搜索文档和引用，但找不到相关信息。我使用的是iOS 6和Xcode 4.5。有人知道这件事吗？提前谢谢