30, leftBarButtonItem rightBarButtonItem 的设置优先级 > backBarButtonItem
backBarButtonItem 的属性需要在 Avc push出 Bvc之前设置 Avc
let bBar = UIBarButtonItem.init(title: "777", style: .done, target: nil, action: nil)
bBar.tintColor = .red
self.navigationItem.backBarButtonItem = bBar
self.navigationController?.pushViewController(checkVC, animated: true)
以上代码实现 push出的控制器 返回箭头为 红色 箭头后的数字为 777 Bvc不能再定义 leftBarButtonItem 否则会覆盖backBarButton