Snippet showing how to create an NSItemProvider with a simulated delay for loading an image

SimulatedSlowLoadingImage.swift

import UIKit
import MobileCoreServices

let image = UIImage() // your actual image

let itemProvider = NSItemProvider()
        
itemProvider.registerDataRepresentation(forTypeIdentifier: kUTTypeJPEG as String, visibility: .all) { (completionBlock) -> Progress? in
    let unitsOfWork = 10 + Int64(arc4random_uniform(UInt32(10))) // 10 - 19 units
    let progress = Progress.discreteProgress(totalUnitCount: unitsOfWork)
    DispatchQueue.global(qos: .userInitiated).async {
        for _ in 0...unitsOfWork {
            // Delay (sleep) 0.2 second for each unit of work
            let delay = UInt32(0.2 * Double(USEC_PER_SEC))
            usleep(delay)
            progress.completedUnitCount += 1
        }
        completionBlock(UIImageJPEGRepresentation(image, 0.8), nil)
    }
    return progress
}