Question

我能够从核心数据中获取数据，但是现在我想用游戏名称列创建一个数组，以便可以使用该数组填充选择器视图

import UIKit
import CoreData

class GameViewController: UIViewController, NSFetchedResultsControllerDelegate, UIPickerViewDelegate, UIPickerViewDataSource {

    var gameCourse: [String] = [String]()
    var frc : NSFetchedResultsController = NSFetchedResultsController<NSFetchRequestResult>()
    var pc = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext

    @IBOutlet weak var inputGameDate: UIDatePicker!
    @IBOutlet weak var inputGameCourse: UIPickerView!

    func fetchRequest() -> NSFetchRequest<NSFetchRequestResult> {

        let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "Course")
        let sorter = NSSortDescriptor(key: "coursename", ascending: true)
        fetchRequest.sortDescriptors = [sorter]

        return fetchRequest
    }

    func getFRC() -> NSFetchedResultsController<NSFetchRequestResult> {

        frc = NSFetchedResultsController(fetchRequest: fetchRequest(), managedObjectContext: pc, sectionNameKeyPath: nil, cacheName: nil)
        return frc
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        self.inputGameCourse.delegate = self as UIPickerViewDelegate
        self.inputGameCourse.dataSource = self as UIPickerViewDataSource

        frc = getFRC()
        frc.delegate = self

        do {

            try frc.performFetch()
        }
        catch {

            print (error)
            return
        }

        //self.pickerView.reloadData()

        gameCourse = ["Eagle Canyon","Ruimsig"]
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    // Number of columns of data
    func numberOfComponents(in pickerView: UIPickerView) -> Int {
        return 1
    }

    // The number of rows of data
    func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
        return gameCourse.count
    }

    // The data to return fopr the row and component (column) that's being passed in
    func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
        return gameCourse[row]
    }

    /*
    // MARK: - Navigation

    // In a storyboard-based application, you will often want to do a little preparation before navigation
    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        // Get the new view controller using segue.destination.
        // Pass the selected object to the new view controller.
    }
    */

}

Answer 1

首先，您可能想对Course个对象运行请求：

func fetchRequest() -> NSFetchRequest<Course> {
    let fetchRequest = NSFetchRequest<Course>(entityName: "Course")
    let sorter = NSSortDescriptor(key: "coursename", ascending: true)
    fetchRequest.sortDescriptors = [sorter]

    return fetchRequest
}

然后实际执行请求并从结果中获取名称：

do {
   let courses: [Course] = try pc.fetch(fetchRequest())
   gameCourse = courses.map(course -> course.coursename)
} catch {
   print(error)
   return
}

Answer 2

在您的课程中实现此静态方法（NSManagedObject）并像Course.sortedCourses

一样使用它

tsconfig.json

根据收到的核心数据创建阵列

2 个答案: