xcode 如何使用核心数据保存和显示图像 - swift 3

How do I save and show a Image with core data - swift 3

提问by H.N.

I am doing a project in Swift 3- xcode 8, and I am trying to use core data to save and show some images in a data base table "users". This image is the user photo in his profile.

我正在做一个项目Swift 3- xcode 8，我正在尝试使用核心数据在数据库表“用户”中保存和显示一些图像。这张图片是他个人资料中的用户照片。

Now I've managed to save strings and showing them from core data but I am having problems in working this out with images.

现在我已经设法保存字符串并从核心数据中显示它们，但是我在用图像解决这个问题时遇到了问题。

This is what I have so far:

这是我到目前为止：

Adding USERS into core data

将 USERS 添加到核心数据中

func addUser() {
    let app = UIApplication.shared.delegate as! AppDelegate
    let context = app.persistentContainer.viewContext
    let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Users")
    request.returnsObjectsAsFaults = false

    let newUser = NSEntityDescription.insertNewObject(forEntityName: "Users", into: context)

    if (firstName.text == "" && lastName.text == "" && contact.text == "" && email.text == "") { //if we have a user profile delete it
        deleteUser()
    } else { // add a new user profile
        newUser.setValue(firstName.text, forKey: "firstName")
        newUser.setValue(lastName.text, forKey: "lastName")
        newUser.setValue(contact.text, forKey: "contact")
        newUser.setValue(email.text, forKey: "email")

        //newUser.setValue(imageView.image, forKey: "photo")
        //let imgUrl = UIImagePickerControllerReferenceURL as! NSURL
        let img = UIImage(named: "f.png")
        let imgData = UIImageJPEGRepresentation(img!, 1)

        newUser.setValue(imgData, forKey: "photo")

        print ("Data added in Users")
    }
    do {
        try context.save()
        //print("saved!!!")
        Alert.show(title: "Success", message: "Profile Saved", vc: self)
    } catch {
       // print ("Error")
        Alert.show(title: "Error", message: "Profile not Saved", vc: self)
    }
}

Showing Usersfrom core data

显示用户来自core data

func showUser() {
    let app = UIApplication.shared.delegate as! AppDelegate
    let context = app.persistentContainer.viewContext
    let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Users")

    request.returnsObjectsAsFaults = false

    do {
        let results = try context.fetch(request)

        if results.count > 0 {
            print("Profile: Data Found:")
            for result in results as! [NSManagedObject] {
               if let firstNameinData = result.value(forKey: "firstName") as? String{
                    firstName.text = firstNameinData
                    print(firstNameinData)
                }

                if let lastNameinData = result.value(forKey: "lastName") as? String{
                    lastName.text = lastNameinData
                    print(lastNameinData)
                }

                if let contactinData = result.value(forKey: "contact") as? String{
                    contact.text = contactinData
                    print(contactinData)
                }

                if let emailinData = result.value(forKey: "email") as? String{
                    email.text = emailinData
                    print(emailinData)
                }

                if let photoinData = result.value(forKey: "photo") as? UIImage{
                    imageView.image = photoinData
                }
            }
        } else {  // if there is not a user profile
            firstName.text = ""
            lastName.text = ""
            contact.text = ""
            email.text = ""
            print("Profile : No data found")
        }
        //print("Loaded!!!")
    } catch {
        print ("Error Loading")
    }
}

I cannot show the image I have saved. Do you have any tips?

我无法显示我保存的图像。你有什么建议吗？

EDIT: Xcode gives me this message "Connection to assetsd was interrupted or assetsd died"

编辑：Xcode 给我这条消息“连接到 assetsd 被中断或 assetsd 死了”

回答by Larme

The property photoof Usersis (NS)Data, as you do there, converting the

该物业photo的Users是(NS)Data，当你在那里做，转换

UIImageinto NSData.

UIImage进入NSData。

let img = UIImage(named: "f.png")
let imgData = UIImageJPEGRepresentation(img!, 1)
newUser.setValue(imgData, forKey: "photo")

While when you retrieve the info, you are doing like photowas a UIImageobject:

当您检索信息时，您所做的就像photo是一个UIImage对象：

if let photoinData = result.value(forKey: "photo") as? UIImage{
    imageView.image = photoinData
}

This is not logical according to previous lines. It should be something like that:

根据前几行，这不合逻辑。它应该是这样的：

if let imageData = result.value(forKey: "photo") as? NSData {
    if let image = UIImage(data:imageData) as? UIImage {
        imageView.image = image
    }
}

Note: I don't speak Swift, so the proposed code may not compile, but you should get the idea of what's wrong and what's need to be done.

注意：我不会说 Swift，因此建议的代码可能无法编译，但您应该了解什么是错误的以及需要做什么。

回答by Manvir Singh

Hope i helps you. work fine for me

希望我能帮到你。对我来说很好用

var results :[Any] = []

let image = UIImage(named: "image.png")
        //this is the line that appears to be wrong
        let imageData = UIImagePNGRepresentation(image!) as NSData?



        guard let appDelegate =
            UIApplication.shared.delegate as? AppDelegate else {
                return
        }


        // 1
        let managedContext =
            appDelegate.persistentContainer.viewContext

        // 2
        let entity =
            NSEntityDescription.entity(forEntityName: "Image",
                                       in: managedContext)!

        let person = NSManagedObject(entity: entity,
                                     insertInto: managedContext)

        // 3
        person.setValue(imageData, forKeyPath: "name")

        // 4
        do {
            try managedContext.save()
            results.append(person)


        } catch let error as NSError {
            print("Could not save. \(error), \(error.userInfo)")
        }

回答by Rolf Cosmo Anthony

Larme has it almost spot on, but instead of this:

Larme 几乎找到了它，但不是这样：

if let image = UIImage(data:imageData) as? UIImage

do this:

做这个：

if let image = UIImage(data: imageData as Data)

回答by Bhuvaneswari Lakshminarayanan

Hope this will help you. First I too had a great confusing of storing the image in core Data.

希望这会帮助你。首先，我也很困惑将图像存储在核心数据中。

This is used to save the image in coreData

这用于将图像保存在 coreData 中

First create Nsmanaged Object Class

首先创建 Nsmanaged 对象类

class Item: NSManagedObject {


}

Declare the image as NSData

import CoreData

extension Item {

    @NSManaged var image: NSData?
    @NSManaged var name: String?
    @NSManaged var email: String?

}

Now go the View Controller you want to save the image .

现在转到要保存图像的视图控制器。

class newViewController: UIViewController ,UIImagePickerControllerDelegate,UINavigationControllerDelegate{

 var item : Item? = nil

    var imagePicker = UIImagePickerController()

    var PassImages = UIImage()

    @IBOutlet var name: UITextField!

    @IBOutlet var email: UITextField!

    @IBOutlet var photoclick: UIButton!

        var context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext


    @IBAction func clickaction(_ sender: Any) {

        if UIImagePickerController.isSourceTypeAvailable(UIImagePickerController.SourceType.photoLibrary){
            print("Button capture")

            let picker = UIImagePickerController()
            picker.allowsEditing = true
            picker.sourceType = .photoLibrary
            picker.delegate = self  //Don't forget this line!
            self.present(picker, animated: true, completion: nil)


        }
    }


    func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {

        var selectedImage: UIImage?
        if let editedImage = info[.editedImage] as? UIImage {
            selectedImage = editedImage
            self.image.image = selectedImage!
            picker.dismiss(animated: true, completion: nil)
        } else if let originalImage = info[.originalImage] as? UIImage {
            selectedImage = originalImage
            self.image.image = selectedImage!
            picker.dismiss(animated: true, completion: nil)
        }

    }


    func imagePickerControllerDidCancel(picker: UIImagePickerController!) {

        self.dismiss(animated: true, completion: nil)
    }

    @IBOutlet var image: UIImageView!=nil


    @IBAction func submit(_ sender: Any) {

        if name.text != "" && email.text != ""
        {

            let entityDescription = NSEntityDescription.entity(forEntityName: "Table", in: context)

            let item = Item(entity: entityDescription!, insertInto: context)

            item.name = name.text
            item.email = email.text

            item.image = image.image!.pngData()! as NSData

            do {
                try context.save()
                print("saved this moc")
            } catch {
                return
            }

 let UserDetailsVc = self.storyboard?.instantiateViewController(withIdentifier: "ViewController") as! ViewController

            self.navigationController?.pushViewController(UserDetailsVc, animated: true)

        }
        else
        {
            print("mail check")
            let alertController1 = UIAlertController (title: "Fill Email id", message: "Enter valid email", preferredStyle: UIAlertController.Style.alert)

            alertController1.addAction(UIAlertAction(title: "OK", style: .default, handler: nil))
            present(alertController1, animated: true, completion: nil)
        }
    }

override func viewDidLoad() {

        super.viewDidLoad()

        if item != nil {
            name.text = item?.name
            email.text = item?.email
            image.image = UIImage(data: (item?.image)! as Data)
        }
    }

This controller is used to fetch everything

此控制器用于获取所有内容

class ViewController: UIViewController ,UITableViewDataSource,UITableViewDelegate,NSFetchedResultsControllerDelegate{

    var userarray: [Table] = []

    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return userarray.count
    }

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

        let cell = tableView.dequeueReusableCell(withIdentifier: "TableViewCell", for: indexPath) as! TableViewCell

        let name = userarray[indexPath.row]
        cell.username.text = name.name

        cell.showImage?.image = UIImage(data: (name.image)!)

         return cell
    }

    @IBOutlet var table: UITableView!
    override func viewDidLoad() {
        super.viewDidLoad()

        fetchData()
    }

    override func viewWillAppear(_ animated: Bool) {
        fetchData()
    }

    func fetchData(){

        let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext

        do {
            userarray = try context.fetch(Table.fetchRequest())
            print(userarray,"user")

        }catch{
            print("error")
        }

    }

}