在iOS 8.0中，Apple引入了UIAlertController来代替UIActionSheet。不幸的是，Apple没有添加有关如何呈现它的任何信息。我在hayaGeek的博客上找到了关于它的条目，但是，它似乎在iPad上不起作用。该视图完全放错了位置：
放错位置：
正确：
我使用以下代码在界面上显示它：
let alert = UIAlertController()
// setting buttons
self.presentModalViewController(alert, animated: true)是否有另一种方法可以将其添加到iPad？还是苹果只是忘记了iPad，或者尚未实现？
Answers:
您可以使用UIAlertController来显示弹出窗口中的UIPopoverPresentationController。
UIViewController *self; // code assumes you're in a view controller
UIButton *button; // the button you want to show the popup sheet from
UIAlertController *alertController;
UIAlertAction *destroyAction;
UIAlertAction *otherAction;
alertController = [UIAlertController alertControllerWithTitle:nil
message:nil
preferredStyle:UIAlertControllerStyleActionSheet];
destroyAction = [UIAlertAction actionWithTitle:@"Remove All Data"
style:UIAlertActionStyleDestructive
handler:^(UIAlertAction *action) {
// do destructive stuff here
}];
otherAction = [UIAlertAction actionWithTitle:@"Blah"
style:UIAlertActionStyleDefault
handler:^(UIAlertAction *action) {
// do something here
}];
// note: you can control the order buttons are shown, unlike UIActionSheet
[alertController addAction:destroyAction];
[alertController addAction:otherAction];
[alertController setModalPresentationStyle:UIModalPresentationPopover];
UIPopoverPresentationController *popPresenter = [alertController
popoverPresentationController];
popPresenter.sourceView = button;
popPresenter.sourceRect = button.bounds;
[self presentViewController:alertController animated:YES completion:nil];对于Swift 4.2进行编辑，尽管可以使用许多博客，但是可以节省搜索时间。
if let popoverController = yourAlert.popoverPresentationController {
popoverController.sourceView = self.view //to set the source of your alert
popoverController.sourceRect = CGRect(x: self.view.bounds.midX, y: self.view.bounds.midY, width: 0, height: 0) // you can set this as per your requirement.
popoverController.permittedArrowDirections = [] //to hide the arrow of any particular direction
}在iPad上，警报将使用新的UIPopoverPresentationController显示为弹出窗口，它要求您使用sourceView和sourceRect或barButtonItem为弹出窗口的显示指定锚点
为了指定锚点，您将需要获取对UIAlertController的UIPopoverPresentationController的引用，并设置以下属性之一：
alertController.popoverPresentationController.barButtonItem = button;样例代码：
UIAlertAction *actionDelete = nil;
UIAlertAction *actionCancel = nil;
// create action sheet
UIAlertController *alertController = [UIAlertController
alertControllerWithTitle:actionTitle message:nil
preferredStyle:UIAlertControllerStyleActionSheet];
// Delete Button
actionDelete = [UIAlertAction
actionWithTitle:NSLocalizedString(@"IDS_LABEL_DELETE", nil)
style:UIAlertActionStyleDestructive handler:^(UIAlertAction *action) {
// Delete
// [self deleteFileAtCurrentIndexPath];
}];
// Cancel Button
actionCancel = [UIAlertAction
actionWithTitle:NSLocalizedString(@"IDS_LABEL_CANCEL", nil)
style:UIAlertActionStyleCancel handler:^(UIAlertAction *action) {
// cancel
// Cancel code
}];
// Add Cancel action
[alertController addAction:actionCancel];
[alertController addAction:actionDelete];
// show action sheet
alertController.popoverPresentationController.barButtonItem = button;
alertController.popoverPresentationController.sourceView = self.view;
[self presentViewController:alertController animated:YES
completion:nil];在Swift 2中，您想要执行以下操作以在iPhone和iPad上正确显示它：
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)
}如果未设置演示者，则会在iPad -[UIPopoverPresentationController presentationTransitionWillBegin]上出现以下消息，最终导致异常：
致命异常：NSGenericException您的应用程序展示了一个UIAlertControllerStyleActionSheet样式的UIAlertController（<UIAlertController：0x17858a00>）。具有此样式的UIAlertController的modalPresentationStyle是UIModalPresentationPopover。您必须通过警报控制器的popoverPresentationController提供此弹出窗口的位置信息。您必须提供sourceView和sourceRect或barButtonItem。如果在显示警报控制器时不知道此信息，则可以在UIPopoverPresentationControllerDelegate方法-prepareForPopoverPresentation中提供它。
Swift 3.0及更高版本的更新
let actionSheetController: UIAlertController = UIAlertController(title: "SomeTitle", message: nil, preferredStyle: .actionSheet)
let editAction: UIAlertAction = UIAlertAction(title: "Edit Details", style: .default) { action -> Void in
print("Edit Details")
}
let deleteAction: UIAlertAction = UIAlertAction(title: "Delete Item", style: .default) { action -> Void in
print("Delete Item")
}
let cancelAction: UIAlertAction = UIAlertAction(title: "Cancel", style: .cancel) { action -> Void in }
actionSheetController.addAction(editAction)
actionSheetController.addAction(deleteAction)
actionSheetController.addAction(cancelAction)
// present(actionSheetController, animated: true, completion: nil) // doesn't work for iPad
actionSheetController.popoverPresentationController?.sourceView = yourSourceViewName // works for both iPhone & iPad
present(actionSheetController, animated: true) {
print("option menu presented")
}2018更新
由于这个原因，我刚拒绝了一个应用程序，因此非常快速的解决方案就是将操作表更改为警报。
很有魅力，并且顺利通过了App Store测试人员。
可能不是每个人都合适的答案，但我希望这可以帮助您中的一些人摆脱困境。
Swift 4及以上
我创建了一个扩展
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 = []
}
}
}如何使用：
let actionSheetVC = UIAlertController(title: "Title", message: nil, preferredStyle: .actionSheet)
addActionSheetForIpad(actionSheet: actionSheetVC)
present(actionSheetVC, animated: true, completion: nil)这是一个快速的解决方案：
NSString *text = self.contentTextView.text;
NSArray *items = @[text];
UIActivityViewController *activity = [[UIActivityViewController alloc]
initWithActivityItems:items
applicationActivities:nil];
activity.excludedActivityTypes = @[UIActivityTypePostToWeibo];
if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPad) {
//activity.popoverPresentationController.sourceView = shareButtonBarItem;
activity.popoverPresentationController.barButtonItem = shareButtonBarItem;
[self presentViewController:activity animated:YES completion:nil];
}
[self presentViewController:activity animated:YES completion:nil];斯威夫特5
我为iPhone使用了“动作表”样式，为iPad使用了“警报”样式。iPad显示在屏幕中央。无需指定sourceView或将视图锚定在任何地方。
var alertStyle = UIAlertController.Style.actionSheet
if (UIDevice.current.userInterfaceIdiom == .pad) {
alertStyle = UIAlertController.Style.alert
}
let alertController = UIAlertController(title: "Your title", message: nil, preferredStyle: alertStyle)编辑：根据ShareToD的建议，不建议使用更新的“ UI_USER_INTERFACE_IDIOM（）== UIUserInterfaceIdiom.pad”检查
对我来说，我只需要添加以下内容：
if let popoverController = alertController.popoverPresentationController {
popoverController.barButtonItem = navigationItem.rightBarButtonItem
}在展示您的操作表之前，只需添加以下代码：
if let popoverController = optionMenu.popoverPresentationController {
popoverController.sourceView = self.view
popoverController.sourceRect = CGRect(x: self.view.bounds.midX, y: self.view.bounds.midY, width: 0, height: 0)
popoverController.permittedArrowDirections = []
}