Core Data from code

context は View から受け取る他ない？

参照

swift

let fetchRequest = NSFetchRequest<NSFetchRequestResult>()
fetchRequest.entity = Category.entity()
guard let categories = try? context.fetch(fetchRequest) as? [Category] else {
	return
}
for category in categories {
	print(category.name ?? "-")
}

削除

swift

for category in categories {
	context.delete(category)
}

新規作成 ( + 親子階層 )

swift

for x in ["金融", "英語", "IT"] {
	let category = Category(context: context)
	category.name = "xxx \(x)"
	let notebook = Notebook(context: context)
	notebook.category = category // <-- 子から親を指定している
	notebook.name = "\(x) メモ"
}

保存 ( 各操作の最後にやる )

swift

do {
	try context.save()
} catch {
	let nsError = error as NSError
	fatalError("Unresolved error \(nsError), \(nsError.userInfo)")
}