iOS - iPad 的 viewWillTransition 中错误的 UIScreen 边界

Question

我必须检查我的设备在 iOS 8+ 中是否改变了方向。

我的做法是:

override func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) {
    super.viewWillTransition(to: size, with: coordinator)

    let isLand = UIScreen.main.bounds.width > UIScreen.main.bounds.height

    coordinator.animate(alongsideTransition: nil) { _ in
        let isLand2 = UIScreen.main.bounds.width > UIScreen.main.bounds.height


        print("\(isLand) -> \(isLand2)")
    }
}

它在 iPhone 中运行良好，但在 iPad 中，isLand 已经有了应该在定向完成之后的新值，所以:

人像 > 风景:true -> true

横向 > 纵向:false -> false

根据文档，边界应该随着方向改变，所以它应该有一个前/后边界，不是吗？

UIScreen main bounds:

This rectangle is specified in the current coordinate space, which takes into account any interface rotations in effect for the device. Therefore, the value of this property may change when the device rotates between portrait and landscape orientations.

如果我像这样使用当前 Root View Controller 的边界，它在 iPhone 和 iPad 上都能正常工作:

override func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) {
    super.viewWillTransition(to: size, with: coordinator)

    let isLand = UIApplication.shared.keyWindow!.rootViewController!.view.bounds.width > UIApplication.shared.keyWindow!.rootViewController!.view.bounds.height

    coordinator.animate(alongsideTransition: nil) { _ in
        let isLand2 = UIApplication.shared.keyWindow!.rootViewController!.view.bounds.width > UIApplication.shared.keyWindow!.rootViewController!.view.bounds.height


        print("\(isLand) -> \(isLand2)")
    }
}

纵向 > 横向:false -> true

横向 > 纵向:true -> false

Answer 1

您应该尝试使用协调器上下文的 containerView。

override func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) {
    super.viewWillTransition(to: size, with: coordinator)

    let isLand = coordinator.containerView.bounds.width > coordinator.containerView.bounds.height

    coordinator.animate(alongsideTransition: nil) { _ in
        let isLand2 = coordinator.containerView.bounds.width > coordinator.containerView.bounds.height

        print("\(isLand) -> \(isLand2)")
    }

}

如果您想获得有关转换的更多信息，您可以使用 func view(forKey: UITransitionContextViewKey) 和 func viewController(forKey: UITransitionContextViewControllerKey) 使用 .from 键。