let predicate = NSPredicate(format: "name == %@", "Tommy")
let options = [CKQuerySubscription.Options.firesOnRecordDeletion, 			  CKQuerySubscription.Options.firesOnRecordCreation, CKQuerySubscription.Options.firesOnRecordUpdate]
let subscription = CKQuerySubscription(recordType: recordType, predicate: predicate, subscriptionID: subscriptionID, options: options)

let notificationInfo = CKSubscription.NotificationInfo()
// 开启静默推送
notificationInfo.shouldSendContentAvailable = true
// 普通推送
notificationInfo.alertBody = "Tommy"
notificationInfo.shouldBadge = true

subscription.notificationInfo = notificationInfo

CKContainer.default().publicCloudDatabase.save(subscription) { (subscription, error) in
    // TODO:
}

import UserNotifications

UNUserNotificationCenter.current().requestAuthorization(options: [.alert, .sound, .badge]) { (accepted, error) in
    // TODO:
}

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
    application.registerForRemoteNotifications()
    return true
}

func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable : Any]) {
    let cloudKitNotification = CKNotification(fromRemoteNotificationDictionary: userInfo)
    
    if(cloudKitNotification?.subscriptionID == subscriptionID) {
    	if(cloudKitNotification?.notificationType == CKNotification.NotificationType.query) {
            let queryNotification = cloudKitNotification as! CKQueryNotification
            let recordID = queryNotification.recordID

            // TODO
        }
	}
}

// 这里注意，如果 previousServerChangeToken 为 nil，那么就是获取所有的 changes
let changesOperation = CKFetchDatabaseChangesOperation(previousServerChangeToken: nil) 

changesOperation.fetchAllChanges = true

// 保存所有有改变的 zoneID
changesOperation.recordZoneWithIDChangedBlock = { zoneID in
    self.changedZoneIDs.append(zoneID)
}
// 删除本地的数据
changesOperation.recordZoneWithIDWasDeletedBlock = { zoneID in
                                                    
}
// token 更新
changesOperation.changeTokenUpdatedBlock = { token in
     
}

changesOperation.fetchDatabaseChangesCompletionBlock = { (newToken: CKServerChangeToken?, more: Bool, error: Error?) in
    // 如果上面 changesOperation.fetchAllChanges = false， 那么 changes 有可能会分段返回
    // 这里的 more 就用来标识后面是否还有 changes
      
    // 在这个缓存 token 下次使用
    // 用官方的话说就是 saving the change token at the end of the operation 
                                                        
    // 根据 changedZoneIDs 获取 zone 中 record 的改变
	self.fetchZoneChanges(changedZoneIDs) 
}
self.privateDB.add(changesOperation)

func fetchZoneChanges(recordZoneIDs: [CKRecordZone.ID]) {
    // 可以通过 optionsByRecordZoneID 设置 token、resultLimit 等
    let changesOperation = CKFetchRecordZoneChangesOperation(recordZoneIDs: recordZoneIDs, optionsByRecordZoneID: nil)
    
    // record 改变
    changesOperation.recordChangedBlock = { record in
                                           
    }
    // record 删除
    changesOperation.recordWithIDWasDeletedBlock = { (recordID, recordType) in
                                                    
    }
    // 某个 zone 的 changToken 更新
    changesOperation.recordZoneChangeTokensUpdatedBlock = { (zoneID, token, tokenData) in
                                                           
    }
    // 某个 zone 的 fetchChanges 操作完成
    changesOperation.recordZoneFetchCompletionBlock = { (zoneID, token, tokenData, moreComing, error) in
    	// 在这个缓存 token 下次使用
        // 用官方的话说就是 saving the change token at the end of the operation                                              
    }
    // 所有 zone 的 fetchChanges 操作完成
    changesOperation.fetchRecordZoneChangesCompletionBlock = { error in
                                                              
    }
    
    self.privateDB.add(changesOperation)
}

public struct CloudArchiver {
    public static func archiver<T: NSSecureCoding>(_ obj: T) -> Data {
        // obtain the metadata from the CKRecord
        let data = NSMutableData()
        let coder = NSKeyedArchiver(forWritingWith: data)
        coder.requiresSecureCoding = true
        obj.encode(with: coder)
        coder.finishEncoding()
        
        return data as Data
    }
    
    public static func unarchiver<T: NSSecureCoding>(_ data: Data) -> T? {
        let coder = NSKeyedUnarchiver(forReadingWith: data)
        coder.requiresSecureCoding = true
        let obj = T(coder: coder)
        coder.finishDecoding()
        
        return obj
    }
}


// 使用
let data = CloudArchiver.archiver(token)
let token: CKServerChangeToken = CloudArchiver.unarchiver(data)

// obtain the metadata from the CKRecord
let data = NSMutableData()
let coder = NSKeyedArchiver.init(forWritingWith: data)
coder.requiresSecureCoding = true
record.encodeSystemFields(with: coder)
coder.finishEncoding()
// 缓存 data


// set up the CKRecord with its metadata
let coder = NSKeyedUnarchiver(forReadingWith: yourLocalObject.encodedSystemFields!)
coder.requiresSecureCoding = true
let record = CKRecord(coder: coder)
coder.finishDecoding()
// write your custom fields...