斯威夫特3:

class func openShareActions(image: UIImage, vc: UIViewController) {
    let activityVC = UIActivityViewController(activityItems: [image], applicationActivities: nil)
    if UIDevice.current.userInterfaceIdiom == .pad {
        if activityVC.responds(to: #selector(getter: UIViewController.popoverPresentationController)) {
            activityVC.popoverPresentationController?.sourceView = vc.view
        }
    }
    vc.present(activityVC, animated: true, completion: nil)
}

我找到了这个解 首先，你呈现弹窗的视图控制器应该实现<UIPopoverPresentationControllerDelegate>协议。

接下来，你需要设置popoverPresentationController的委托。

添加以下功能:

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
// Assuming you've hooked this all up in a Storyboard with a popover presentation style
    if ([segue.identifier isEqualToString:@"showPopover"]) {
        UINavigationController *destNav = segue.destinationViewController;
        PopoverContentsViewController *vc = destNav.viewControllers.firstObject;

        // This is the important part
        UIPopoverPresentationController *popPC = destNav.popoverPresentationController;
        popPC.delegate = self;
    }
}

- (UIModalPresentationStyle)adaptivePresentationStyleForPresentationController: (UIPresentationController *)controller {
    return UIModalPresentationNone;
}

同样的问题也出现在我的项目中，然后我找到了解决方案，在iPad中打开UIActivityViewController，我们必须使用UIPopoverController

下面是在iPhone和iPad上使用它的代码:

//to attach the image and text with sharing 
UIImage *image=[UIImage imageNamed:@"giraffe.png"];
NSString *str=@"Image form My app";
NSArray *postItems=@[str,image];

UIActivityViewController *controller = [[UIActivityViewController alloc] initWithActivityItems:postItems applicationActivities:nil];

//if iPhone
if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone) {
    [self presentViewController:controller animated:YES completion:nil];
}
//if iPad
else {
    // Change Rect to position Popover
    UIPopoverController *popup = [[UIPopoverController alloc] initWithContentViewController:controller];
    [popup presentPopoverFromRect:CGRectMake(self.view.frame.size.width/2, self.view.frame.size.height/4, 0, 0)inView:self.view permittedArrowDirections:UIPopoverArrowDirectionAny animated:YES];
}

对于swift 4.2 / swift 5

func openShareDilog() {
    let text = "share text will goes here"

    // set up activity view controller
    let textToShare = [text]
    let activityViewController = UIActivityViewController(activityItems: textToShare, applicationActivities: nil)
    activityViewController.excludedActivityTypes = [.airDrop]

    if let popoverController = activityViewController.popoverPresentationController {
        popoverController.sourceRect = CGRect(x: UIScreen.main.bounds.width / 2, y: UIScreen.main.bounds.height / 2, width: 0, height: 0)
        popoverController.sourceView = self.view
        popoverController.permittedArrowDirections = UIPopoverArrowDirection(rawValue: 0)
    }

    self.present(activityViewController, animated: true, completion: nil)
}

解决Objective-C和使用UIPopoverPresentationController

    UIActivityViewController *controller = /*Init your Controller*/;
    //if iPhone
    if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone) {
        [self presentViewController:controller animated:YES completion:nil];
    }
    //if iPad
    else {
        UIPopoverPresentationController* popOver = controller.popoverPresentationController
        if(popOver){
            popOver.sourceView = controller.view;
            popOver.sourceRect = CGRectMake(self.view.frame.size.width/2, self.view.frame.size.height/4, 0, 0);
            [self presentViewController:controller animated:YES completion:nil];
        }
    }

在Swift修复这个iPad，最好的方法是这样做，我发现。

    let things = ["Things to share"]
    let avc = UIActivityViewController(activityItems:things, applicationActivities:nil)
    avc.setValue("Subject title", forKey: "subject")
    avc.completionWithItemsHandler = {
        (s: String!, ok: Bool, items: [AnyObject]!, err:NSError!) -> Void in
    }

    self.presentViewController(avc, animated:true, completion:nil)
    if let pop = avc.popoverPresentationController {
        let v = sender as! UIView // sender would be the button view tapped, but could be any view
        pop.sourceView = v
        pop.sourceRect = v.bounds
    }

如果你在点击UIBarButtonItem时显示UIActivityViewController，请使用以下代码:

activityViewController.popoverPresentationController?.barButtonItem = sender

否则，如果你使用另一个控件，例如UIButton，使用以下代码:

activityViewController.popoverPresentationController?.sourceView = sender
activityViewController.popoverPresentationController?.sourceRect = sender.bounds

从文档到UIPopoverPresentationController:

var barButtonItem: UIBarButtonItem? { get set }

为此属性分配一个值，以将弹出窗口锚定到指定的栏按钮项。显示时，弹出窗口的箭头指向指定的项。或者，您可以使用sourceView和sourceRect属性为弹出窗口指定锚点位置。