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)

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);

我最近在Swift 2.0中遇到了这个确切的问题(最初的问题)，其中UIActivityViewController在iphone上工作得很好，但在模拟ipad时导致了崩溃。

我只是想在这里补充一点，至少在Swift 2.0中，你不需要if语句。你可以让popoverPresentationController是可选的。

作为一个快速题外话，接受的答案似乎是说，你可以只有一个sourceView，只是一个sourceRect，或只是一个barButtonItem，但根据苹果的文档UIPopoverPresentationController你需要以下之一:

栏按钮项 源视图和源矩形

我正在工作的特定示例如下，在那里我创建了一个函数，接受一个UIView(为sourceView和sourceRect)和字符串(UIActivityViewController的唯一的activityItem)。

func presentActivityViewController(sourceView: UIView, activityItem: String ) {

    let activityViewController = UIActivityViewController(activityItems: [activityItem], applicationActivities: [])

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

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

这段代码适用于iPhone和iPad(我认为甚至是tvOS)——如果设备不支持popoverPresentationController，那么提到它的两行代码基本上会被忽略。

有点好，所有你需要做的，使它工作的ipad只是添加两行代码，或者只是一个如果你使用barButtonItem!

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)
}

Swift = ios7/ ios8

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

//if iPhone
if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiom.Phone) {
    // go on..
} else {
    //if iPad
    if activityViewController.respondsToSelector(Selector("popoverPresentationController")) {
        // on iOS8
        activityViewController.popoverPresentationController!.barButtonItem = self.shareButtonItem;
    }
}
self.presentViewController(activityViewController, animated: true, completion: nil)

我尝试了下一个代码，它工作:

首先在视图控制器中放入一个栏按钮项 然后创建一个IBOutlet:

@property(weak,nonatomic)IBOutlet UIBarButtonItem *barButtonItem;

你的uiactivityviewcontroller . popoverpresentationcontroller . barbuttonitem = self.barButtonItem;