ios - 使用 Swift 将信息从 ViewController 传递到 ViewController

Question

我是编码和 Swift 新手。对于我第一次尝试应用程序，我正在尝试制作一个移动音乐提醒应用程序，我可以在其中输入艺术家、专辑和发行日期，它会通知我专辑今天发布的发行日期。

我正在开发编辑按钮，如果我拼错了艺术家或专辑，甚至弄错了发行日期，我可以进去编辑已保存的信息，并将新数据保存在原始数据上。

目前，我正在尝试将信息从一个 ViewController 传递到另一个 ViewController，但遇到了一些困难。

我需要从 AddfreshreleaseViewController 获取艺术家、专辑和发布日期信息才能转到 EditfreshreleaseViewController

到目前为止，我只是尝试让艺术家信息通过，但我没有任何运气。我观看了视频并阅读了大量文章和书籍，但我似乎无法让它发挥作用。

下面是AddfreshreleaseViewController代码:

 import UIKit
 import CoreData
 import UserNotifications

 class AddfreshreleaseViewController: UIViewController {

@IBOutlet weak var Artist: UITextField!


/* @IBOutlet weak var textfield = UITextField? (artisttextfield!)



let EditfreshreleaseViewController =  segue.destination as! EditfreshreleaseViewController

EditfreshreleaseViewController.receivedString = artisttextfield.text!

}

override func prepare (for segue: UIStoryboardSegue, sender: Any?) {*/


@IBOutlet var artisttextfield: UITextField!
@IBOutlet var albumtextfield: UITextField!
@IBOutlet var releasedatePicker: UIDatePicker!

override func viewDidLoad() {
    super.viewDidLoad()

    releasedatePicker.minimumDate = Date()

    func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?){
        var destinationAddfreshreleaseViewController : EditfreshreleaseViewController = segue.destinationAddfreshreleaseViewController as EditfreshreleaseViewController

        destinationAddfreshreleaseViewController.ArtistText = Artist.text!

    }

    // Do any additional setup after loading the view, typically from a nib.
}
@IBAction func saveTapped( _ sender: UIBarButtonItem) {

    let artist = artisttextfield.text ?? ""
    let album = albumtextfield.text ?? ""
    let releasedate = releasedatePicker.date

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

    let newRelease = Release_Date(context: context)
    newRelease.artist = artist
    newRelease.album = album
    newRelease.release_date = releasedate as NSDate?
    newRelease.release_dateId = UUID().uuidString

    if let uniqueId = newRelease.release_dateId {
        print("The freshreleaseId is \(uniqueId)")
    }

    do {
        try context.save()
        let message = "\(artist)'s new album \(album) releases Today!"
        let content = UNMutableNotificationContent()
        content.body = message
        content.sound = UNNotificationSound.default()
        var dateComponents = Calendar.current.dateComponents([.month, .day],
            from: releasedate)
        dateComponents.hour = 09
        dateComponents.minute = 00
        let trigger = UNCalendarNotificationTrigger(dateMatching: dateComponents,
            repeats: true)
        if let identifier = newRelease.release_dateId {

            let request = UNNotificationRequest(identifier: identifier,
                content: content, trigger: trigger)
            let center = UNUserNotificationCenter.current()
            center.add(request, withCompletionHandler: nil)
        }
    } catch let error {
        print("Could not save because of \(error).")
    }

    dismiss(animated: true, completion: nil)

    print("Added a Release Date!")
    print("Artist: \(newRelease.artist)")
    print("Album: \(newRelease.album)")
    print("Release Date: \(newRelease.release_date)")
}

@IBAction func cancelTapped(_ sender: UIBarButtonItem) {
    dismiss(animated: true, completion: nil)
}



}

下面是 EditfreshreleaseViewController 代码:

 import UIKit
 import CoreData
 import UserNotifications

 class EditfreshreleaseViewController: UIViewController {

@IBOutlet var Artist: UITextField!

var ArtistText = String()

@IBOutlet var artisttextfield: UITextField!
@IBOutlet var albumtextfield: UITextField!
@IBOutlet var releasedatePicker: UIDatePicker!
/*@IBOutlet weak var artist: UILabel! (ArtistTextField!)
    var receivedString = ""*/


override func viewDidLoad() {

    Artist.text = ArtistText

    super.viewDidLoad()

    /*artist.text = receivedString*/

    releasedatePicker.minimumDate = Date()

    // Do any additional setup after loading the view, typically from a nib.
}
@IBAction func saveTapped( _ sender: UIBarButtonItem) {

    let artist = artisttextfield.text ?? ""
    let album = albumtextfield.text ?? ""
    let releasedate = releasedatePicker.date

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

    let newRelease = Release_Date(context: context)
    newRelease.artist = artist
    newRelease.album = album
    newRelease.release_date = releasedate as NSDate?
    newRelease.release_dateId = UUID().uuidString

    if let uniqueId = newRelease.release_dateId {
        print("The freshreleaseId is \(uniqueId)")
    }

    do {
        try context.save()
        let message = "\(artist)'s new album \(album) releases Today!"
        let content = UNMutableNotificationContent()
        content.body = message
        content.sound = UNNotificationSound.default()
        var dateComponents = Calendar.current.dateComponents([.month, .day],
                                                             from: releasedate)
        dateComponents.hour = 09
        dateComponents.minute = 00
        let trigger = UNCalendarNotificationTrigger(dateMatching: dateComponents,
                                                    repeats: true)
        if let identifier = newRelease.release_dateId {

            let request = UNNotificationRequest(identifier: identifier,
                                                content: content, trigger: trigger)
            let center = UNUserNotificationCenter.current()
            center.add(request, withCompletionHandler: nil)
        }
    } catch let error {
        print("Could not save because of \(error).")
    }

    dismiss(animated: true, completion: nil)

    print("Added a Release Date!")
    print("Artist: \(newRelease.artist)")
    print("Album: \(newRelease.album)")
    print("Release Date: \(newRelease.release_date)")
}

@IBAction func cancelTapped(_ sender: UIBarButtonItem) {
    dismiss(animated: true, completion: nil)
}



 }

任何帮助将不胜感激。

Answer 1

prepareForSegue 函数是一个 UIViewController 方法，必须由子类重写，以便通过 segue 在其他 ViewController 之间传递数据。

尝试将 AddfreshreleaseViewController 中的代码编辑为以下内容。 (我基本上从 viewDidLoad 函数中删除了一些代码，并在其下方添加了一个新代码)

override func viewDidLoad() {
    super.viewDidLoad()

    releasedatePicker.minimumDate = Date()
}

override func prepareForSegue(for segue: UIStoryboardSegue, sender: Any?) {
    if let destination = segue.destination as? EditfreshreleaseViewController{
        destination.ArtistText = Artist.text!
    }
}