我已经创建了一个PFObject的子类,基本上遵循了
parse.com docs上的指令,并在本地固定了对象.解析文档似乎没有用于检索PFObject子类,我想知道 – 是否可以将检索到的对象转换为PFObject子类.如果是这样,怎么样？
(我知道如果不可能,可能需要根据PFObject的检索属性重新实例化子类.)
let query = PFQuery(className:Armor.parseClassName())
query.fromLocalDatastore()
query.findObjectsInBackgroundWithBlock({
(objects:[AnyObject]?,error: NSError?) in
if let error = error {
// There was an error
} else {
if let objects = objects as? [PFObject] {
for object in objects {
//This println is outputting to the console:
println("PFObject object retrieved")
if let object = object as? Armor {
//This println is NOT outputting to the console:
println("PFObject object cast as Armor")
}
}
}
}
})
确保您已在应用程序中注册了子类：didFinishLaunchingWithOptions：.在我的例子中,它不会将检索到的对象强制转换为PFObject子类.
func application(application: UIApplication,didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
Armor.registerSubclass()
Parse.enableLocalDatastore()
Parse.setApplicationId(...,clientKey: ...)
return true
}
AppDelegate.swift
func application(application: UIApplication,didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
CatsObject.registerSubclass()
Parse.enableLocalDatastore()
Parse.setApplicationId("...",clientKey: "...")
return true
}
CatsObject.swift
import Foundation
class CatsObject: PFObject,PFSubclassing {
static func parseClassName() -> String {
return "Cat"
}
}
CatViewController.swift
override func viewDidLoad() {
queryData()
}
func queryData() {
let query = PFQuery(className: CatsObject.parseClassName())
query.fromLocalDatastore()
query.findObjectsInBackgroundWithBlock({
(objects:[AnyObject]?,error: NSError?) in
if let error = error {
// There was an error
} else {
println("count local objects = \(objects?.count)")
if let objects = objects as? [PFObject] {
for object in objects {
println("PFObject object retrieved")
if object is CatsObject {
println("object is CatsObject subclass")
}
if let object = object as? CatsObject {
println("PFObject object cast as CatsObject")
}
}
}
}
})
}
控制台输出
count local objects = Optional(10) PFObject object retrieved object is CatsObject subclass PFObject object cast as CatsObject
