导航栏图片按钮颜色问题（笔记）

UIImage *imageBack = [UIImage imageNamed:@"returnBackWhite"];

    imageBack = [imageBack imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];

    UIBarButtonItem *leftBarBtnItem = [[UIBarButtonItem alloc] initWithImage:imageBack style:UIBarButtonItemStylePlain target:self action:@selector(leftBarButtonItemClick:)];

    self.navigationItem.leftBarButtonItem = leftBarBtnItem;

显示图片本身颜色