我有一个 Swift 应用程序,它使用NSFetchedResultsController
获取List
来自持久存储的对象:
let fetchedResultsController: NSFetchedResultsController = ...
var error : NSError?
fetchedResultsController.performFetch(&error)
if let error = error {
NSLog("Error: \(error)")
}
let lists: [List] = fetchedResultsController.fetchedObjects! as [List]
NSLog("lists count = \(lists.count)")
for list: List in lists {
NSLog("List: \(list.description)")
}
它按预期工作,我得到了List
对象描述打印到控制台。
我想为我的应用程序编写一些单元测试,所以我创建了扩展的类XCTestCase
。代码编译没有问题,测试运行,但不幸的是我无法获取List
该上下文中的对象。
我在控制台中得到的只是计数List
对象和致命错误:
lists count = 59
fatal error: NSArray element failed to match the Swift Array Element type
由该行提出:
for list: List in lists {
我很确定我已经正确配置了目标,因为我可以创建List
对象并将其插入到托管对象上下文中,从我的应用程序的源代码以及单元测试源代码都没有问题。我遇到的唯一问题是从测试单元获取。我想知道为什么在模拟器中运行应用程序时提取工作正常,而在单元测试期间执行时提取失败。
任何可能出错的想法将不胜感激。
Update:
为了更具体地说明我的实现方式,这里是我正在使用的完整代码示例:
var error: NSError? = nil
let urls = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)
let applicationDocumentsDirectory = urls[urls.count-1] as NSURL
let modelURL = NSBundle.mainBundle().URLForResource("CheckLists", withExtension: "momd")!
let managedObjectModel = NSManagedObjectModel(contentsOfURL: modelURL)
var coordinator: NSPersistentStoreCoordinator? = NSPersistentStoreCoordinator(managedObjectModel: managedObjectModel)
let url = applicationDocumentsDirectory.URLByAppendingPathComponent("CheckLists.sqlite")
if coordinator!.addPersistentStoreWithType(NSSQLiteStoreType, configuration: nil, URL: url, options: nil, error: &error) == nil {
NSLog("Error1: \(error)")
abort()
}
var managedObjectContext = NSManagedObjectContext()
managedObjectContext.persistentStoreCoordinator = coordinator
let fetchRequest = NSFetchRequest()
fetchRequest.entity = NSEntityDescription.entityForName("List", inManagedObjectContext: managedObjectContext)
fetchRequest.sortDescriptors = [ NSSortDescriptor(key: "name", ascending: true) ]
let fetchedResultsController = NSFetchedResultsController(
fetchRequest: fetchRequest,
managedObjectContext: managedObjectContext,
sectionNameKeyPath: nil,
cacheName: "ListFetchedResultsControllerCache"
)
fetchedResultsController.performFetch(&error)
if let error = error {
NSLog("Error2: \(error)")
abort()
}
let fetchedObjects: [AnyObject]? = fetchedResultsController.fetchedObjects
if let fetchedObjects = fetchedObjects {
NSLog("Fetched objects count: \(fetchedObjects.count)")
for fetchedObject in fetchedObjects {
NSLog("Fetched object: \(fetchedObject.description)")
}
}
else {
NSLog("Fetched objects array is nil")
}
let fetchedLists: [List]? = fetchedResultsController.fetchedObjects as? [List]
if let fetchedLists = fetchedLists {
NSLog("Fetched lists count: \(fetchedLists.count)")
for fetchedList in fetchedLists {
NSLog("Fetched list: \(fetchedList.description)")
}
}
else {
NSLog("Fetched lists array is nil")
}
当我从应用程序的源代码执行它并在模拟器中运行应用程序时,控制台输出如下所示:
Fetched objects count: 3
Fetched object: <CheckLists.List: 0x7a6866f0> (entity: List; id: 0x7a686020 <x-coredata://7A87B5BE-C2FA-4150-B9E3-879FDE07F0B9/List/p2> ; data: {
name = "List 1";
})
Fetched object: <CheckLists.List: 0x7a686930> (entity: List; id: 0x7a686030 <x-coredata://7A87B5BE-C2FA-4150-B9E3-879FDE07F0B9/List/p1> ; data: {
name = "List 2";
})
Fetched object: <CheckLists.List: 0x7a686970> (entity: List; id: 0x7a686040 <x-coredata://7A87B5BE-C2FA-4150-B9E3-879FDE07F0B9/List/p3> ; data: {
name = "List 3";
})
Fetched lists count: 3
Fetched list: <CheckLists.List: 0x7a6866f0> (entity: List; id: 0x7a686020 <x-coredata://7A87B5BE-C2FA-4150-B9E3-879FDE07F0B9/List/p2> ; data: {
name = "List 1";
})
Fetched list: <CheckLists.List: 0x7a686930> (entity: List; id: 0x7a686030 <x-coredata://7A87B5BE-C2FA-4150-B9E3-879FDE07F0B9/List/p1> ; data: {
name = "List 2";
})
Fetched list: <CheckLists.List: 0x7a686970> (entity: List; id: 0x7a686040 <x-coredata://7A87B5BE-C2FA-4150-B9E3-879FDE07F0B9/List/p3> ; data: {
name = "List 3";
})
但是,当我从单元测试中执行此代码时,我得到以下输出:
Fetched objects count: 3
Fetched object: <CheckLists.List: 0x7a07df50> (entity: List; id: 0x7a07d7e0 <x-coredata://7A87B5BE-C2FA-4150-B9E3-879FDE07F0B9/List/p2> ; data: {
name = "List 1";
})
Fetched object: <CheckLists.List: 0x7a07e190> (entity: List; id: 0x7a07d7f0 <x-coredata://7A87B5BE-C2FA-4150-B9E3-879FDE07F0B9/List/p1> ; data: {
name = "List 2";
})
Fetched object: <CheckLists.List: 0x7a07e1d0> (entity: List; id: 0x7a07d800 <x-coredata://7A87B5BE-C2FA-4150-B9E3-879FDE07F0B9/List/p3> ; data: {
name = "List 3";
})
Fetched lists array is nil
我希望它可以更容易地理解问题出在哪里。不知何故,这个声明:
let fetchedLists: [List]? = fetchedResultsController.fetchedObjects as? [List]
产生一个数组List
当应用程序在模拟器中运行时生成对象,但无法生成nil
从单元测试执行时。