Sample cloud kit asset list saving

ViewController.swift

//
//  ViewController.swift
//  AssetSyncTest
//
//  Created by Paul Wilkinson on 12/4/17.
//  Copyright © 2017 Paul Wilkinson. All rights reserved.
//

import UIKit
import CloudKit

class ViewController: UIViewController {
    
    var container: CKContainer!
    var publicDB: CKDatabase!

    
    
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        
        
        container = CKContainer.default()
        
        publicDB = container.publicCloudDatabase
        
        self.doStuff()
        
        
    }
    
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
    
    
    func doStuff() {
        
        let image1 = #imageLiteral(resourceName: "sample1")
        let image2 = #imageLiteral(resourceName: "sample2")
        
        if let asset1 = createAsset(from: UIImagePNGRepresentation(image1)!),
            let asset2 = createAsset(from: UIImagePNGRepresentation(image2)!) {
            
            let record = CKRecord(recordType: "test")
            let assets = [asset1,asset2]
            
            record["assets"] = assets as CKRecordValue
            
            self.saveRecord(record)
            
        }
        
    }
    
    func saveRecord(_ xrecord: CKRecord) {
        let record: [CKRecord] = [xrecord]
        let saveOperation = CKModifyRecordsOperation.init(recordsToSave: record, recordIDsToDelete: nil)
        
        saveOperation.perRecordCompletionBlock = {(record, error) -> Void in
            if let error = error {
                print("error saving record: \(error)")
            }
        }
        
        saveOperation.modifyRecordsCompletionBlock = {(records,ids,error) -> Void in
            if let error = error {
                print("Error saving records: \(error)")
            }
        }
        
        
        publicDB.add(saveOperation)
    }
    
    
    func createAsset(from data: Data) -> CKAsset? {
        
        var returnAsset: CKAsset? = nil
        
        let tempStr = ProcessInfo.processInfo.globallyUniqueString
        
        let filename = "\(tempStr)_file.bin"
        
        let baseURL = URL(fileURLWithPath: NSTemporaryDirectory())
        
        let fileURL = baseURL.appendingPathComponent(filename, isDirectory: false)
        
        do {
            try data.write(to: fileURL, options: [.atomicWrite])
            
            returnAsset = CKAsset(fileURL: fileURL)
            
        } catch {
            print("Error creating asset: \(error)")
        }
        
        return returnAsset
        
    }
    
    
}