Issue sending image using Multipeer Connectivity

Question

I've got an app that uses Multipeer Connectivity to send files between devices. On the receiving device, didFinishReceivingResourceWithNamelocalURL is called, but the file at the localURL seems to be empty. Code below:

func sendPhoto() {
    guard let imageData = UIImagePNGRepresentation(photo) else { return }
    imageData.writeToURL(photoURL, atomically: true)
    // photoURL: "/var/mobile/Containers/Data/Application/0A2C6681-FA7C-4821-8C21-E9C3768E84EC/Documents/temp/A9081EE5-5D43-499D-8DC0-D36FEC041FE0.png"

    session.sendResourceAtURL(photoURL, withName: "image.png", toPeer: otherPeer) { 
        error in
            print(error)
    }
}

func session(session: MCSession, didFinishReceivingResourceWithName resourceName: String,
    fromPeer peerID: MCPeerID, atURL localURL: NSURL, withError error: NSError?) {
        print(error) // error is nil
        do {
            try NSFileManager.defaultManager().moveItemAtURL(localURL, toURL: profilePhotoURL)
            // profilePhotoURL: file:///var/mobile/Containers/Data/Application/FE5CF814-5BD4-40A9-9444-C8776F3153DC/Documents/temp/5535AACE-2C7D-4337-BBCF-8F62BC51239C.png
        } catch { print(error) }

        let image = UIImage(contentsOfFile: profilePhotoURL.absoluteString) // image is nil
}

I've also tried getting the NSData at localURL, but it ends up being nil.

photo is a UIImage selected from the user's photos library. Any thoughts on what could be going wrong?

More Info:

I checked the file system on the receiving device, and the image is there. It seems something is causing the UIImage constructor to fail with any image received over MPC.

Sample Project:

I've written a small reproducer app on GitHub. You'll need two iOS devices to test it out.

Answer 1

I tried this and for me all I had to do was convert to an NSData immediately from the local URL as such:

func session(session: MCSession, didFinishReceivingResourceWithName resourceName: String,
fromPeer peerID: MCPeerID, atURL localURL: NSURL, withError error: NSError?) {
    var image: UIImage? = nil
    if let localData = NSData(contentsOfURL: localURL) {
        image = UIImage(data: localData)
    }
}