调用系统自带的导航栏图片

UIBarButtonItem系统自带的图片

比如可能用到设置的：

设置按钮

//使用系统的gearshape图片
[UIImage systemImageNamed:@"gearshape"];

UIBarButtonItem *leftItem = [[UIBarButtonItem alloc] initWithImage:[UIImage systemImageNamed:@"gearshape"] style:UIBarButtonItemStylePlain target:self action:@selector(returnLastController)];

   //leftItem.tintColor = [UIColor whiteColor];///设置以后图片颜色跟随变化

    self.navigationItem.leftBarButtonItem = leftItem;