我已经在一个新的基于 Swift 的应用程序(目前是 XCode 6 beta 3)中成功地设置了一个 RestKit 到 CoreData 的映射实现。我知道导入映射在我的 RestKit JSON 调用中起作用,因为我可以检查 sqlite 数据库并查看我的数据。但是,我无法从 NSFetchRequest 中的数据存储中取回数据。我做错了什么?
我将保留所有 RestKit 设置和拆卸,因为它非常标准并且看起来运行良好。所以这是我的 AppDelegate 查询代码,它似乎不起作用:
var currentUser: User? {
if !_currentUser {
var error: NSError? = nil
let request = NSFetchRequest(entityName: "User")
let recordCount = self.managedObjectContext.countForFetchRequest(request, error:&error)
NSLog("user records found: \(recordCount)")
var result = self.managedObjectContext.executeFetchRequest(request, error:&error)
for resultItem : AnyObject in result {
_currentUser = resultItem as? User
if _currentUser {
NSLog("Fetched User for \(_currentUser!.firstname) \(_currentUser!.lastname)")
}
}
}
return _currentUser;
}
self.managedObjectContext 从我的 AppDelegate 引用它以从 RestKit shareObject 获取上下文:
var managedObjectContext: NSManagedObjectContext {
return RKObjectManager.sharedManager().managedObjectStore.mainQueueManagedObjectContext
}
看来fetch请求是成功的,因为for/in循环出现了断点。但是,当我检查 resultItem 或 _currentUser 对象时,它们显示为空,并且“if _currentUser”NSLog 永远不会触发。
有什么想法吗?我是否对在 Swift 中取回数据做出了错误的假设?
编辑 2:
问题源于我试图将 resultItem 转换为 Optional。如果在没有可选的情况下声明 _currentUser 并删除 as?可选转换查询返回一个正确的用户对象:
for resultItem : AnyObject in result {
_currentUser = resultItem as User
NSLog("Fetched User for \(_currentUser.firstname) \(_currentUser.lastname)")
}
编辑: 我在主提取请求之前添加了一个记录数,它正确地显示了 1 条记录。所以我试图将获取结果映射到我的用户对象的方式出了点问题。这是我的用户类:
import Foundation
import CoreData
class User: NSManagedObject {
@NSManaged
var id: Int32
@NSManaged
var createdAt: NSDate
@NSManaged
var udpatedAt: NSDate
@NSManaged
var username: String
@NSManaged
var email: String
@NSManaged
var firstname: String
@NSManaged
var lastname: String
@NSManaged
var organization: String
@NSManaged
var tokens: NSArray
}
最佳答案
答案显然是 Swift 不喜欢将获取结果强制转换为可选。我必须将结果放入局部变量,然后设置可选的:
var currentUser: User? {
if !_currentUser {
var error: NSError? = nil
let request = NSFetchRequest(entityName: "User")
let recordCount = self.managedObjectContext.countForFetchRequest(request, error:&error)
NSLog("user records found: \(recordCount)")
var result = self.managedObjectContext.executeFetchRequest(request, error:&error)
for resultItem : AnyObject in result {
var currentUserItem = resultItem as User
NSLog("Fetched User for \(currentUserItem.firstname) \(currentUserItem.lastname)")
_currentUser = currentUserItem
}
}
return _currentUser;
}
这是我在 Swift 中对 RestKit 的设置和拆解,以防有人(比如 niiamon)觉得它有用:
来 self 的 RestApi.swift:
var objectStore: RKManagedObjectStore = RKManagedObjectStore()
init() {
configureRestKit()
}
func configureRestKit() {
let objectManager = RKObjectManager(baseURL: NSURL.URLWithString(baseUrl))
//objectManager.requestSerializationMIMEType = RKMIMETypeJSON;
RKObjectManager.setSharedManager(objectManager)
objectStore = RKManagedObjectStore(managedObjectModel: managedObjectModel())
let dataPath = "\(RKApplicationDataDirectory())/MyApp.sqlite"
NSLog("Setting up store at \(dataPath)")
objectStore.addSQLitePersistentStoreAtPath(dataPath, fromSeedDatabaseAtPath: nil, withConfiguration: nil, options: optionsForSqliteStore(), error: nil)
objectStore.createManagedObjectContexts()
objectStore.managedObjectCache = RKInMemoryManagedObjectCache(managedObjectContext: objectStore.persistentStoreManagedObjectContext)
objectManager.managedObjectStore = objectStore
// -- Declare routes -- //
// Login Route
objectManager.addResponseDescriptor(userLoginResponseDescriptor())
objectManager.addResponseDescriptor(eventLoginResponseDescriptor())
objectManager.router.routeSet.addRoute(RKRoute(name:kUserLoginRouteName, pathPattern: "/login", method: RKRequestMethod.POST))
}
func tearDownRestKit() {
// Cancel any network operations and clear the cache
RKObjectManager.sharedManager().operationQueue.cancelAllOperations()
NSURLCache.sharedURLCache().removeAllCachedResponses()
// Cancel any object mapping in the response mapping queue
RKObjectRequestOperation.responseMappingQueue().cancelAllOperations()
// Ensure the existing defaultStore is shut down
NSNotificationCenter.defaultCenter().removeObserver(RKManagedObjectStore.defaultStore())
RKObjectManager.setSharedManager(nil)
RKManagedObjectStore.setDefaultStore(nil)
}
func userMapping() -> RKEntityMapping {
let userMapping = RKEntityMapping(forEntityForName: "User", inManagedObjectStore: objectStore)
var userDictionary = ["id": "id", "created_at": "createdAt", "updated_at": "updatedAt", "username": "username", "email": "email", "firstname": "firstname", "lastname": "lastname", "organization": "organization"]
userMapping.addAttributeMappingsFromDictionary(userDictionary)
let tokenMapping = RKEntityMapping(forEntityForName: "ApiToken", inManagedObjectStore: objectStore)
tokenMapping.addAttributeMappingsFromArray(["token", "expiration"])
userMapping.addRelationshipMappingWithSourceKeyPath("tokens", mapping:tokenMapping)
return userMapping
}
func userLoginResponseDescriptor() -> RKResponseDescriptor {
let userResponseDescriptor = RKResponseDescriptor(mapping: userMapping(), method: RKRequestMethod.POST, pathPattern: "/login", keyPath: "user", statusCodes: NSIndexSet(index: 200))
return userResponseDescriptor
}
func managedObjectModel() -> NSManagedObjectModel {
return NSManagedObjectModel.mergedModelFromBundles(nil)
}
func optionsForSqliteStore() -> NSDictionary {
return [
NSInferMappingModelAutomaticallyOption: true,
NSMigratePersistentStoresAutomaticallyOption: true
];
}
关于ios - RestKit、CoreData 和 Swift - 我似乎无法取回结果,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/24736739/