ios - 访问 CoreData 属性的问题

Question

我正在像这样在核心数据中保存某个属性 name..

//Saving to CoreData
guard let appDelegate = UIApplication.shared.delegate as? AppDelegate else {
       return
}
let managedContext = appDelegate.persistentContainer.viewContext

let entity = NSEntityDescription.entity(forEntityName: "Category", in: managedContext)

let category = NSManagedObject(entity: entity!, insertInto: managedContext)

category.setValue(name, forKeyPath: "theName")

do {
try managedContext.save()
self.mangObjArr.append(category as! Category)

} catch let error as NSError {
print("Could not save. \(error), \(error.userInfo)")
}

现在我想在另一个 View Controller 中获取此 name 以便我可以将其作为 API 调用中的参数传递。但是我无法弄清楚如何获得名称属性。另外，我不太擅长 Swift，所以问这个问题...:)

Answer 1

您应该有一些关于 Core Data 的好教程，因为这是一个非常基本的问题。我不认为你在这里问问题之前用谷歌搜索过。我会给你解决方案，但不要重复。

let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "Category")
if let fetchedObjects = try? managedContext.fetch(fetchRequest), !fetchedObjects.isEmpty
{
    let category = fetchedObjects.first as? NSManagedObject
    print(category?.value(forKey: "theName"))
}

链接:

https://www.appcoda.com/introduction-to-core-data/

https://www.raywenderlich.com/145809/getting-started-core-data-tutorial

https://code.tutsplus.com/tutorials/core-data-and-swift-managed-objects-and-fetch-requests--cms-25068