我想fetchedResultsController在Swift3中使用我的代码。我尝试过这种方式和其他方式，但我做不到。这是我的代码（不起作用）：
var fetchedResultsController: NSFetchedResultsController<Entity> {
let fetchRequest: NSFetchRequest<Entity>
if #available(iOS 10.0, *) {
fetchRequest = Entity.fetchRequest()
} else {
// Fallback on earlier versions
fetchRequest = NSFetchRequest(entityName: "Entity")
}
fetchRequest.fetchBatchSize = 20
let orderDescriptor = NSSortDescriptor(key: "archiveOrder", ascending: true)
let nameDesctiptor = NSSortDescriptor(key: "entityName", ascending: false)
fetchRequest.sortDescriptors = [orderDescriptor, nameDesctiptor]
let aFetchedResultsController: NSFetchedResultsController<Entity> = NSFetchedResultsController(fetchRequest: fetchRequest, managedObjectContext: appDelegate.managedObjectContext, sectionNameKeyPath: nil, cacheName: "Master")
aFetchedResultsController.delegate = self
_fetchedResultsController = aFetchedResultsController
do {
try _FetchedResultsController.performFetch()
} catch {
let nserror = error as NSError
print("Unresolved error \(nserror), \(nserror.userInfo)")
}
return _FetchedResultsController!
}
您能给我任何建议吗？
基本上，Apple建议NSFetchedResultsController使用闭包声明为非可选的惰性初始化属性，该闭包仅在闭包中运行一次代码。
lazy var fetchedResultsController: NSFetchedResultsController<NSFetchRequestResult> = { ... }()
您的代码无法编译，因为Swift代码区分大小写，这意味着_fetchedResultsController并且_FetchedResultsController是两回事。
其余代码似乎是正确的。
lazy var fetchedResultsController: NSFetchedResultsController<Entity> = {
let fetchRequest: NSFetchRequest<Entity>
if #available(iOS 10.0, *) {
fetchRequest = Entity.fetchRequest()
} else {
// Fallback on earlier versions
fetchRequest = NSFetchRequest(entityName: "Entity")
}
fetchRequest.fetchBatchSize = 20
let orderDescriptor = NSSortDescriptor(key: "archiveOrder", ascending: true)
let nameDesctiptor = NSSortDescriptor(key: "entityName", ascending: false)
fetchRequest.sortDescriptors = [orderDescriptor, nameDesctiptor]
let aFetchedResultsController = NSFetchedResultsController(fetchRequest: fetchRequest,
managedObjectContext: appDelegate.managedObjectContext,
sectionNameKeyPath: nil,
cacheName: "Master")
aFetchedResultsController.delegate = self
do {
try aFetchedResultsController.performFetch()
} catch {
let nserror = error as NSError
print("Unresolved error \(nserror), \(nserror.userInfo)")
}
return aFetchedResultsController
}()
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