ios - 如何在 Activity View Controller 中为每个平台共享不同的图片？

Question

我正在使用 native Swift 制作一个应用程序，用户可以在其中使用 Activity View Controller (AVC) 共享预制图像。这些图像的分辨率非常高，为 1024x1024，但是当这些图像转发到 iOS7 上的“消息”时，顶部和底部会被截断。当图像为 128x128 或在 iOS8 上共享任何分辨率时，确实会发生这种情况。

由于我在显示 AVC 之前将图像作为 PNGDataRepresentation 输入，我想知道是否有一种方法可以根据用户选择的平台输入不同的图像。如果用户选择消息，我基本上会指向较低分辨率的 Assets ，如果选择保存或 Facebook 共享，我会指向高分辨率 Assets 。

func openShareWidget ()
{

    var activityProvider: ShareActivityProvider = ShareActivityProvider();
    activityProvider.currentType = self.currentType;

    var imageData : NSData = UIImagePNGRepresentation(selectedCell.getSharingImage());
    var activityItems : NSArray = [activityProvider, imageData];

    var activityController : SharingActivityViewController = SharingActivityViewController(activityItems: activityItems, applicationActivities: []);

    presentViewController(activityController, animated: true, completion: nil);
}     

我的 ActivityProvider 扩展实现如下:

class ShareActivityProvider: UIActivityItemProvider, UIActivityItemSource {

var currentType : ImageType!;

override func activityViewController(activityViewController: UIActivityViewController, itemForActivityType activityType: String) -> AnyObject?
{
    switch activityType
    {
        case UIActivityTypeMail:
            return "" ;
        case UIActivityTypeMessage:
            return "";
        case UIActivityTypePostToFacebook:
            return "Facebook"
        case UIActivityTypePostToTwitter:
            return "Twitter";
        default:
            return "";
    }
}

override func activityViewControllerPlaceholderItem(activityViewController: UIActivityViewController) -> AnyObject
{
    return "";
}

Answer 1

我已经通过使用多个 UIActivityItem 提供程序实现了这一点。一个提供消息正文的文本，而第二个提供图像本身。

func openShareWidget ()
{

    var textProvider : ShareTextActivityProvider = ShareTextActivityProvider(); // same as ShareActivityProvider from question       
    var imgProvider : ShareImageActivityProvider = ShareImageActivityProvider()

    var activityItems : NSArray = [textProvider, imgProvider];

    var activityController : SharingActivityViewController = SharingActivityViewController(activityItems: activityItems, applicationActivities: []);

    presentViewController(activityController, animated: true, completion: nil);
}

这是 ShareImageActivityProvider

class ShareImageActivityProvider: UIActivityItemProvider {

var selectedCell : ImageCell!;

override func activityViewController(activityViewController: UIActivityViewController, itemForActivityType activityType: String) -> AnyObject?
{
    return UIImagePNGRepresentation(selectedCell.getSharingImage(activityType)); 
}

override func activityViewControllerPlaceholderItem(activityViewController: UIActivityViewController) -> AnyObject
{
    return "";
}

}

获取共享图像:

func getSharingImage(activityType : String) -> UIImage
  {
    switch activityType
        {
        case UIActivityTypeMessage:
            return UIImage(named: imgPathLOW);
        case UIActivityTypePostToFacebook, UIActivityTypeMail, UIActivityTypePostToTwitter:
            return UIImage(named: imgPathHD);
        default:
            return UIImage(named: "Tex_Empty");
    }
}