使用Swift將信息從ViewController傳遞到ViewController

Question

我是編碼和Swift的新手。 對於我第一次嘗試使用某個應用程序的過程，我嘗試制作一個移動音樂提醒應用程序，在該應用程序中，我可以鍵入Artist，專輯和發行日期，並且它將在發行日期通知我該專輯今天發行。

我正在使用“編輯”按鈕，如果我拼寫錯誤的Artist或Album甚至錯誤的Release Date，則可以進入並編輯已經保存的信息，並將新數據保存在原始文件上。

目前，我正在嘗試將信息從一個ViewController傳遞到另一個ViewController，但是遇到了一些困難。

我需要來自AddfreshreleaseViewController的Artist，專輯和發行日期信息才能進入EditfreshreleaseViewController

到目前為止，我只是試圖通過Artist信息，但我沒有任何運氣。 我看過視頻並閱讀了許多文章和書籍，但似乎無法正常工作。

下面是AddfreshreleaseViewController代碼：

 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代碼：

 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)
}



 }

任何幫助將不勝感激。

Answer 1

prepareForSegue函數是UIViewController方法，必須通過子類覆蓋該方法，以便通過segue在其他ViewController之間傳遞數據。

嘗試將AddfreshreleaseViewController中的代碼編輯為以下內容。 （我基本上已經從您的viewDidLoad函數中刪除了一些代碼，並在其下面添加了一個新代碼）

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!
    }
}