ORM to map Parse PFObject to native Swift 2.0 class structure, allowing easier migration from CoreData

ParseORM.swift

//
//  ParseORM.swift
//
//  Copyright © 2016 Mobile Flow LLC. All rights reserved.
//

import UIKit
import Parse

class ParseORM : NSObject {
    
    var class_name: String
    var uuid: String
    var createdAt : NSDate
    var parseObj: PFObject? = nil
    
    override init() {
        self.uuid = NSUUID().UUIDString
        self.class_name = String(self.dynamicType)
        self.createdAt = NSDate()
    }
    
    // Initialize object with Parse object
    required convenience init(newParseObj:PFObject){
        self.init()
        
        self.parseObj = newParseObj
        
        let newUUID = newParseObj["uuid"]
        self.uuid = String(newUUID)
        
        let newCreatedAt = newParseObj["createdAt"] as? NSDate
        self.createdAt = newCreatedAt ?? NSDate()
        
        self.parseObj!.pinInBackground()
        
        for keyName in self.props() {
            let keyValue = self.parseObj![keyName]
            if keyValue == nil || keyValue is NSNull { break }     // If nil or NSNull, skip
            if !(keyValue is PFObject) {
                // If property exists
                if (self.respondsToSelector(NSSelectorFromString(keyName))) {
                    self.setValue(keyValue, forKey: keyName)
                }
            }
            else {
                print(keyValue)
            }
        }
    }
    
    
    func save() {
        // Synchronous save method
        if self.parseObj == nil {
            self.parseObj = PFObject(className: self.class_name)
            self.parseObj!["uuid"] = self.uuid
            self.parseObj!["createdAt"] = self.createdAt
            self.parseObj!.pinInBackground()
        }
        
        for keyName in self.props() {
            // If property exists
            if (self.respondsToSelector(NSSelectorFromString(keyName))) {
                var valueObj = self.valueForKey(keyName)
                if valueObj == nil || valueObj is  NSNull { valueObj = NSNull() }
                if valueObj is ParseORM {
                    valueObj = valueObj?.parseObj
                }
                self.parseObj!.setValue(valueObj, forKey: keyName)
            }
        }
        
    }
    
    class func fetchAll() -> [ParseORM] {
        
        let query = PFQuery(className: String(self))
        query.fromLocalDatastore()
        query.orderByDescending("createdAt")
        let results = try! query.findObjects()
        
        var objects = [ParseORM]()
        for obj in results {
            let nativeObj = self.init(newParseObj: obj)
            objects.append(nativeObj)
        }
        
        return objects
    }
    
    
    class func fetchAllInBackground( completionHandler: ([ParseORM]?, NSError?) -> () ) {
        
        let query = PFQuery(className: String(self))
        query.fromLocalDatastore()
        query.orderByDescending("createdAt")
        query.findObjectsInBackgroundWithBlock { (results: [PFObject]?, error: NSError?) -> Void in
            guard error != nil else { completionHandler(nil, error); return }
            guard results != nil else { completionHandler(nil, nil); return }
            
            var objects = [ParseORM]()
            for obj in results! {
                let nativeObj = self.init(newParseObj: obj)
                objects.append(nativeObj)
            }
            
            completionHandler(objects,nil)
            
        }
    }
    
    
    // Utilities
    
    
    // Method to determine the properties of a given subclass
    func props()->[String]{
        var s = [String]()
        for c in Mirror(reflecting: self).children
        {
            if let name = c.label{
                s.append(name)
            }
        }
        return s
    }
    
    
}