在swift 4下面的代码工作在iphone和ipad。 根据文档

对于给定的设备习惯用法，使用适当的方法来呈现和解散视图控制器是你的责任。在iPad上，你必须在弹出窗口中显示视图控制器。在其他设备上，你必须以模态方式呈现它。

 let activityViewController = UIActivityViewController(activityItems: activityitems, applicationActivities: nil)

    if UIDevice.current.userInterfaceIdiom == .pad {

        if activityViewController.responds(to: #selector(getter: UIViewController.popoverPresentationController)) {
            activityViewController.popoverPresentationController?.sourceView = self.view
        }
    }

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

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)
}

使用Xamarin.iOS解决方案。

在我的示例中，我正在进行屏幕捕获，生成图像，并允许用户共享图像。iPad上的弹出窗口位于屏幕中间。

var activityItems = new NSObject[] { image };
var excludedActivityTypes = new NSString[] {
    UIActivityType.PostToWeibo,
    UIActivityType.CopyToPasteboard,
    UIActivityType.AddToReadingList,
    UIActivityType.AssignToContact,
    UIActivityType.Print,
};
var activityViewController = new UIActivityViewController(activityItems, null);

//set subject line if email is used
var subject = new NSString("subject");
activityViewController.SetValueForKey(NSObject.FromObject("Goal Length"), subject);

activityViewController.ExcludedActivityTypes = excludedActivityTypes;
//configure for iPad, note if you do not your app will not pass app store review
if(null != activityViewController.PopoverPresentationController)
{
    activityViewController.PopoverPresentationController.SourceView = this.View;
    var frame = UIScreen.MainScreen.Bounds;
    frame.Height /= 2;
    activityViewController.PopoverPresentationController.SourceRect = frame;
}
this.PresentViewController(activityViewController, true, null);

我使用Swift 5。 当我在iPad上的应用程序中点击“分享按钮”时，我也遇到了同样的问题。找到了这个解。 步骤1:将“view”对象(在对象库中搜索“UIView”)添加到Main.storyboard。 步骤2:在ViewController.swift中创建一个@IBOutlet并分配任意名称(例如:view1)

步骤3:添加上述名称(例如:view1)作为sourceView。这是我的“分享按钮”动作。

@IBAction func Share(_ sender: Any) {
    let activityVC = UIActivityViewController(activityItems: ["www.google.com"], applicationActivities: nil)
    activityVC.popoverPresentationController?.sourceView = view1

    self.present(activityVC, animated: true, completion: nil)


}

我对swift很陌生，在这个问题上耽搁了一个星期。希望这能帮助到一些人。分享这个解。

修复了Swift 2.0

    if UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiom.Phone {
        self.presentViewController(activityVC, animated: true, completion: nil)
    }
    else {
        let popup: UIPopoverController = UIPopoverController(contentViewController: activityVC)
        popup.presentPopoverFromRect(CGRectMake(self.view.frame.size.width / 2, self.view.frame.size.height / 4, 0, 0), inView: self.view, permittedArrowDirections: UIPopoverArrowDirection.Any, animated: true)
    }

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];
        }
    }