iOS - 约束 - VFL 安全区适配

1         if #available(iOS 11.0, *) {
2             tableview.translatesAutoresizingMaskIntoConstraints = false
3             tableview.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor).isActive = true
4         } else {
5             tableview.topAnchor.constraint(equalTo: view.topAnchor).isActive = true
6         }