iOS 横竖屏实践(UIKit)

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present 场景

关注点

present 页面时,重点是这两个属性:

override var supportedInterfaceOrientations: UIInterfaceOrientationMask
override var preferredInterfaceOrientationForPresentation: UIInterfaceOrientation
  • supportedInterfaceOrientations:页面允许方向
  • preferredInterfaceOrientationForPresentation:模态展示时首选方向

必须满足的规则

preferredInterfaceOrientationForPresentation 必须包含在 supportedInterfaceOrientations 中。

错误示例:

override var supportedInterfaceOrientations: UIInterfaceOrientationMask {
    .landscape
}

override var preferredInterfaceOrientationForPresentation: UIInterfaceOrientation {
    .portrait
}

iOS 16 及以下会崩溃:

preferredInterfaceOrientationForPresentation 'portrait' must match a supported interface orientation: 'landscapeLeft, landscapeRight'!

iOS 17 为警告,不崩溃,但仍属于非法配置。

与应用级方向的关系

present 页面还必须与应用级可用方向有交集。
若应用只允许竖屏,而被 present 页面只支持横屏,会出现:

Supported orientations has no common orientation with the application...

推荐写法

override var supportedInterfaceOrientations: UIInterfaceOrientationMask {
    .landscape
}

override var preferredInterfaceOrientationForPresentation: UIInterfaceOrientation {
    .landscapeRight
}

如果需要在多个页面混用横竖屏,可在 AppDelegate 放开应用级方向:

func application(_ application: UIApplication, supportedInterfaceOrientationsFor window: UIWindow?) -> UIInterfaceOrientationMask {
    .all
}

push 场景

关注点

push 页面只用看:

override var supportedInterfaceOrientations: UIInterfaceOrientationMask

preferredInterfaceOrientationForPresentation 不是 push 的控制项。

与应用级方向的关系

如果应用级只允许竖屏,即使页面声明横屏,也不会崩溃,但横屏不会生效。

iOS 版本行为

iOS 15 及以下

从竖屏页 push 到横屏页,不会自动旋转,需要手动触发:

let value: UIInterfaceOrientation = orientation.contains(.landscapeRight) ? .landscapeRight : .portrait
UIDevice.current.setValue(value.rawValue, forKey: "orientation")
UIViewController.attemptRotationToDeviceOrientation()

iOS 16 及以上

会自动旋转。
如需显式请求方向更新,可用 iOS 16 新接口:

guard let windowScene = self.view.window?.windowScene else {
    return
}
let preferences = UIWindowScene.GeometryPreferences.iOS(interfaceOrientations: orientation)
windowScene.requestGeometryUpdate(preferences) { _ in }
self.setNeedsUpdateOfSupportedInterfaceOrientations()