如何对存储的核心数据的数字（Int16）求和

如何对存储的核心数据的数字（Int16）求和 - Swift 3(How to sum the numbers(Int16) of stored core data - Swift 3)

我已经在核心数据中存储了字母（String），数字（Int16）和日期（Date）。 过滤器（NSPredicate）成功地只组织了必要的数据。

我想得到这个核心数据中数字的总和。

实体名称：实体 属性名称：字母（字符串），值（Int16），日期（日期）

let context = (UIApplication.shared.delegate as! AppDelegate).managedObjectContext let entityDesc: NSEntityDescription = NSEntityDescription.entity(forEntityName: "Entity", in: context)! let request: NSFetchRequest<NSFetchRequestResult> = NSFetchRequest() request.entity = entityDesc // Omit date NSFormatter let dateCheck = formatter.string(from: today) request.predicate = NSPredicate(format: "Date == %@", dateCheck) let records = try! context.fetch(request)

我不知道接下来该做什么。 我是一名发展初学者，希望有人可以提供帮助。

I have stored the letters(String), numbers(Int16) and Date(Date) in the core data. And the filter(NSPredicate) succeeded in organizing only the necessary data.

I want to get the total sum of the numbers in this core data.

Entity Name : Entity Attribute Name : Letter(String), Value(Int16), Date(Date)

let context = (UIApplication.shared.delegate as! AppDelegate).managedObjectContext let entityDesc: NSEntityDescription = NSEntityDescription.entity(forEntityName: "Entity", in: context)! let request: NSFetchRequest<NSFetchRequestResult> = NSFetchRequest() request.entity = entityDesc // Omit date NSFormatter let dateCheck = formatter.string(from: today) request.predicate = NSPredicate(format: "Date == %@", dateCheck) let records = try! context.fetch(request)

I do not know what to do next. I am a beginner in development and hope someone can help.

最满意答案

您已经获取了记录，因此以这种方式获取Value属性的总和。

try! context.fetch(request) as! [NSManagedObject] let sum = result.reduce(0) { $0 + ($1.value(forKey: "Value") as? Int16 ?? 0) } print(sum)

You have already fetch the records, so get the sum of the Value attribute this way.

try! context.fetch(request) as! [NSManagedObject] let sum = result.reduce(0) { $0 + ($1.value(forKey: "Value") as? Int16 ?? 0) } print(sum)