Question

我想在swift 3中更新核心数据对象。经过一些谷歌搜索后，我没有发现任何关于swift 3的内容。所以我的问题是：如何在swift 3中更新核心数据对象？

Answer 1

使用带谓词的提取请求获取现有值。在谓词中使用唯一值。获取对象后，使用新值更新对象并保存上下文。

let empId = "001"
let fetchRequest:NSFetchRequest<NSFetchRequestResult> = NSFetchRequest.init(entityName: "EmpDetails")
let predicate = NSPredicate(format: "empId = '\(empId)'")
fetchRequest.predicate = predicate
do {
    let result = try persistentContainer.viewContext.fetch(fetchRequest)
    if let objectToUpdate = result.first as? NSManagedObject {
        objectToUpdate.setValue("newName", forKey: "name")
        objectToUpdate.setValue("newDepartment", forKey: "department")
        objectToUpdate.setValue("001", forKey: "empID")
        do {
            try persistentContainer.viewContext.save()
        } catch {
            print(error)
        }
    }
} catch {
    print(error)
}

Answer 2

在变量“ id”（在Core数据模型中创建的唯一变量）和要更新值的所有变量中传递唯一ID：

func context() ->  NSManagedObjectContext {
    let context=(UIApplication.shared.delegate as!AppDelegate).persistentContainer.viewContext
        return context
}



func save() {
    (UIApplication.shared.delegate as! AppDelegate).saveContext()
}

func UpdateCartByTestId(id:Int64,name:String) {
    let fetchRequest =
            NSFetchRequest<NSManagedObject>(entityName: "Update")
    fetchRequest.returnsObjectsAsFaults = false
    fetchRequest.predicate = NSPredicate(format:"id == %d",id)

    let result = try? context().fetch(fetchRequest)

    if result?.count == 1 {

        let dic = result![0]
        dic.setValue(id, forKey: "id")
        dic.setValue(name, forKey: "name")
        save()
    }
}

更新核心数据对象swift 3

2 个答案: