如何根据输入的日期对核心数据数组进行排序

问题描述

我有一个小的核心数据模型，该模型存储一个字符串数组(搜索历史记录).

I have a small Core Data Model which stores an array of Strings (search history).

在获取数据时，我想按创建时间进行排序.我目前在模型中只有一个名为searchHistory的属性，是否可以使用以下代码(key:对数据进行排序，还是需要向模型添加保存的时间?

When fetching the Data I'd like to sort by the time created. I currently just have one property in my model called searchHistory is there a way I can use the following code (key: to sort the data or will I need to add a time saved to the model?

let request = NSFetchRequest<NSFetchRequestResult>(entityName: entityName)
        request.sortDescriptors = [NSSortDescriptor.init(key: "", ascending: true)]

推荐答案

是的，您需要一个声明为非可选Date的第二个属性，例如dateCreated.在NSManagedObject子类中，覆盖awakeFromInsert以分配创建记录时的当前日期.

Yes, you need a second attribute declared as non-optional Date for example dateCreated. In the NSManagedObject subclass override awakeFromInsert to assign the current date when the record is created.

override func awakeFromInsert() {
    super.awakeFromInsert()
    dateCreated = Date()
}

然后您可以排序

request.sortDescriptors = [NSSortDescriptor(key: "dateCreated", ascending: true)]

按ascending顺序表示最早的条目排在最前面.

in ascending order means the oldest entry comes first.

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