一行代码巧妙实现iOS返回button:
self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc]initWithImage:[[UIImage imageNamed:@"back"] imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal] style:UIBarButtonItemStyleDone target:self.navigationController action:@selector(popViewControllerAnimated:)];
原文：http://www.cnblogs.com/zsychanpin/p/6970306.html