在iOS 8.0中，苹果引入了UIAlertController来取代UIActionSheet。不幸的是，苹果没有提供任何关于如何展示的信息。我在hayaGeek的博客上找到了一个关于它的条目，然而，它似乎不能在iPad上运行。这种观点是完全错误的:
错误的:
正确的:
我使用以下代码在界面上显示它:
let alert = UIAlertController()
// setting buttons
self.presentModalViewController(alert, animated: true)
是否有其他方法添加到iPad上?或者苹果只是忘记了iPad，或者还没有推出iPad ?
当前回答
对我来说，我只需要添加以下内容:
if let popoverController = alertController.popoverPresentationController {
popoverController.barButtonItem = navigationItem.rightBarButtonItem
}
其他回答
2018年更新
我刚刚因为这个原因拒绝了一款应用，而我的一个快速解决方法便是将操作表单改为提醒。
很有魅力，顺利通过了App Store测试。
可能不是每个人都适合这个答案，但我希望这能帮助你们中的一些人迅速摆脱困境。
斯威夫特4.2 你可以像这样使用condition:
let alert = UIAlertController(title: nil, message: nil, preferredStyle: UIDevice.current.userInterfaceIdiom == .pad ? .alert : .actionSheet)
Swift 4及以上
我已经创建了一个扩展
extension UIViewController {
public func addActionSheetForiPad(actionSheet: UIAlertController) {
if let popoverPresentationController = actionSheet.popoverPresentationController {
popoverPresentationController.sourceView = self.view
popoverPresentationController.sourceRect = CGRect(x: self.view.bounds.midX, y: self.view.bounds.midY, width: 0, height: 0)
popoverPresentationController.permittedArrowDirections = []
}
}
}
使用方法:
let actionSheetVC = UIAlertController(title: "Title", message: nil, preferredStyle: .actionSheet)
addActionSheetForiPad(actionSheet: actionSheetVC)
present(actionSheetVC, animated: true, completion: nil)
斯威夫特5
适用于iPad和iPhone。
动作表下方悬停一个按钮
对于iPhone，动作表将显示正常，iPad将显示在按钮下方。
actionSheet.popoverPresentationController?.sourceView = fooButton
actionSheet.popoverPresentationController?.sourceRect = fooButton.bounds
动作表在屏幕/视图的中间
对于iPhone，动作表将正常显示，iPad将显示在屏幕/视图的中间。
actionSheet.popoverPresentationController?.sourceView = view
actionSheet.popoverPresentationController?.sourceRect = CGRect(x: view.bounds.midX, y: view.bounds.midY, width: 0, height: 0)
actionSheet.popoverPresentationController?.permittedArrowDirections = []
在Swift 2中，你想要在iPhone和iPad上正确地显示它:
func confirmAndDelete(sender: AnyObject) {
guard let button = sender as? UIView else {
return
}
let alert = UIAlertController(title: NSLocalizedString("Delete Contact?", comment: ""), message: NSLocalizedString("This action will delete all downloaded audio files.", comment: ""), preferredStyle: .ActionSheet)
alert.modalPresentationStyle = .Popover
let action = UIAlertAction(title: NSLocalizedString("Delete", comment: ""), style: .Destructive) { action in
EarPlaySDK.deleteAllResources()
}
let cancel = UIAlertAction(title: NSLocalizedString("Cancel", comment: ""), style: .Cancel) { action in
}
alert.addAction(cancel)
alert.addAction(action)
if let presenter = alert.popoverPresentationController {
presenter.sourceView = button
presenter.sourceRect = button.bounds
}
presentViewController(alert, animated: true, completion: nil)
}
如果你不设置演示器，你将在iPad上出现一个异常-[UIPopoverPresentationController presentationTransitionWillBegin]，并显示以下消息:
Fatal Exception: NSGenericException Your application has presented a UIAlertController (<UIAlertController: 0x17858a00>) of style UIAlertControllerStyleActionSheet. The modalPresentationStyle of a UIAlertController with this style is UIModalPresentationPopover. You must provide location information for this popover through the alert controller's popoverPresentationController. You must provide either a sourceView and sourceRect or a barButtonItem. If this information is not known when you present the alert controller, you may provide it in the UIPopoverPresentationControllerDelegate method -prepareForPopoverPresentation.
