小编jah*_*ven的帖子

当我打电话

UIApplication.shared.keyWindow

要尝试在我的测试类中设置根视图控制器，键窗口将返回nil。为什么会这样呢？

这是我设置情节提要的方法：

let testBoard = UIStoryboard(name: "TestStoryboard", bundle: Bundle(for: type(of: self)))
let vc = testBoard.instantiateViewController(withIdentifier: "TestController")

UIApplication.shared.keyWindow?.rootViewController = vc

_ = vc.view
vc.viewDidLoad()