设置导航栏顶部返回箭头的颜色及去掉字

//此句写在当前控制器 

//改变顶部导航栏返回箭头的颜色

self.navigationController.navigationBar.tintColor = [UIColor whiteColor];

//去掉返回箭头旁边的文字

self.navigationItem.backBarButtonItem = [[UIBarButtonItem alloc]initWithTitle:@"  "   style:UIBarButtonItemStylePlain target:self action:nil];