在核心数据中使用索引来获取特定的二进制数据

我下面的快速代码将2张单独的图像保存到核心数据中。我想做的是,当用户在文本字段enter 1中键入1时,输入到核心数据中的第一个图像出现在imaegview图片上。如果键入2,则第二张图像出现在imageview上。我的代码基于此,而不是二进制数据。我在pic.image = user.image遇到编译错误,提示无法分配类型为“ Data”的值?键入“ UIImage?”。 https://github.com/redrock34/be

在核心数据中使用索引来获取特定的二进制数据

 import UIKit
import CoreData


class ViewController: UIViewController,UITextFieldDelegate {


    @IBOutlet var labelName : UILabel!
    @IBOutlet var enterT : UITextField!
    @IBOutlet var pic : UIImageView!
    lazy var context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext


    var dx = [UIImage]()
    var names = [String]()

    override func viewDidLoad() {
        super.viewDidLoad()


        enterT.delegate = self

        pic.backgroundColor = .cyan


        guard let appDelegate = UIApplication.shared.delegate as? AppDelegate else { return }
        let managedContext = appDelegate.persistentContainer.viewContext
        let entity = NSEntityDescription.entity(forEntityName: "Users",in: managedContext)!
        let item = NSManagedObject(entity: entity,insertInto: managedContext)
             let item2 = NSManagedObject(entity: entity,insertInto: managedContext)
        let fetch = NSFetchRequest<NSFetchRequestResult>(entityName: "Users")

        let vex = UIImage(named: "on.jpg")?.pngData()
        if let data = vex{
            item.setvalue(data,forKey: "image")

        }




        let vex2 = UIImage(named: "house.jpg")?.pngData()
        if let data2 = vex2{
            item2.setvalue(data2,forKey: "image")
        }




             do {
                 let result = try? managedContext.fetch(fetch) as? [Users]
                 print("Queen",result?.count)
                 try? managedContext.save()



             }
             catch {
                 print("Could not save")
             }


    }


    func textField(_ textField: UITextField,shouldChangeCharactersIn range: NSRange,replacementString string: String) -> Bool {

        guard let text = (textField.text as? NSString)?.replacingCharacters(in: range,with: string),let index = Int(text) else { //here....
            // display an alert about invalid text
            return true
        }
        save(at: index )
        return true
    }

    func save(at index : Int) {
        let fetchRequest = NSFetchRequest<Users>(entityName: "Users")
        fetchRequest.predicate = NSPredicate(format: "idx == %d",Int32(index))
        do {
            if let user = try context.fetch(fetchRequest).first {
                pic.image = user.image
            }
        } catch {
            print("Could not fetch \(error) ")
        }
        return
    }

    @IBaction func add(){


        fetch()
    }

    func fetch()
    {



        for i in 0..<dx.count {
            let newUser = Users(context: context)
            newUser.username = names[i]
            newUser.idx = Int32(i + 1)


        }
        print("Storing Data..")
        do {
            try context.save()
        } catch {
            print("Storing data Failed",error)
        }
        return
    }


}
liync 回答:在核心数据中使用索引来获取特定的二进制数据

您需要将Data类型的图像转换为UIImage,如下所示。

UIImage(data: user.image ?? Data())
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