Proof of concept of sharing to Instagram Stories from SwiftUI

InstagramShareView.swift

import SwiftUI

struct InstagramShareView: View {

  var imageToShare: Image {
    // An image defined in your app's asset catalogue.
    return Image("SomeImage")
  }

  var body: some View {
    VStack {

      // Display the image that will be shared to Instagram.
      imageToShare

      if InstagramSharingUtils.canOpenInstagramStories {
        Button(action: { InstagramSharingUtils.shareToInstagramStories(imageToShare.uiImage) }) {
          Text("Share to Instagram Stories")
        }
      } else {
        Text("Instagram is not available.")
      }
    }
  }
}

InstagramSharingUtils.swift

/*
See https://developers.facebook.com/docs/instagram/sharing-to-stories/ for full reference.
*/

import Foundation
import SwiftUI // You can import UIKit instead if you like, both will work.

struct InstagramSharingUtils {

  // Returns a URL if Instagram Stories can be opened, otherwise returns nil.
  private static var instagramStoriesUrl: URL? {
    if let url = URL(string: "instagram-stories://share?source_application=uk.sdonnelly.personal-best-0") {
      if UIApplication.shared.canOpenURL(url) {
        return url
      }
      return nil
    }
    return nil
  }

  // Convenience wrapper to return a boolean for `instagramStoriesUrl`
  static var canOpenInstagramStories: Bool {
    return instagramStoriesUrl != nil
  }

  // If Instagram Stories is available, writes the image to the pasteboard and
  // then opens Instagram.
  static func shareToInstagramStories(_ image: UIImage) {

    // Check that Instagram Stories is available.
    guard let instagramStoriesUrl = instagramStoriesUrl else {
      return
    }

    // Convert the image to data that can be written to the pasteboard.
    let imageDataOrNil = UIImage.pngData(image)
    guard let imageData = imageDataOrNil() else {
      Logging.error("🙈 Image data not available.")
      return
    }
    let pasteboardItem = ["com.instagram.sharedSticker.backgroundImage": imageData]
    let pasteboardOptions = [UIPasteboard.OptionsKey.expirationDate: Date().addingTimeInterval(60 * 5)]

    // Add the image to the pasteboard. Instagram will read the image from the pasteboard when it's opened.
    UIPasteboard.general.setItems([pasteboardItem], options: pasteboardOptions)

    // Open Instagram.
    UIApplication.shared.open(instagramStoriesUrl, options: [:], completionHandler: nil)
  }
}