Question

我有两个ViewController，FirstViewController和SecondViewController。在SecondViewController上有UISlider。在FirstViewController上有一个警报。

现在我要传输UISlider值，该值是要在FirstViewController上报警的音量。

ps。我要设置的功能与默认的iPhone设置滑块完全相同。

我会很高兴，所以请你们把我的知识告诉我。

import UIKit
import AVFoundation

class FirstViewController: UIViewController, AVAudioPlayerDelegate, 
UITableViewDelegate, UITableViewDataSource{

let TODO = ["A", "B", "C"]

let notificationCenter = NotificationCenter.default
var volume = Float()
var counter = 0
var timer = Timer()
var startTime:Double = 0.0
var audioPlayer: AVAudioPlayer!
@IBOutlet weak var tableView: UITableView!

@IBAction func firstSwitch(_ sender: UISwitch)
{
    if (sender).isOn
    {
        timer = Timer.scheduledTimer(withTimeInterval: 1 * 1, repeats: false, block: { timer in


            self.audioPlayer.play()

            self.audioPlayer.numberOfLoops = -1
            print(self.audioPlayer.isPlaying)
        })
    }else{
        timer.invalidate()
        print("switch1stopped")
        self.audioPlayer.stop()
    }
}

    notificationCenter.addObserver(self, selector: #selector(catchNotification(notification:)), name: NSNotification.Name(rawValue: "test"), object: nil)

}

@objc func catchNotification(notification: Notification) -> Void {
    print("Catch notification")
    audioPlayer.volume = volumeChane.value
    //Use of unresolved identifier 'volumeChane'
}

///////////////////////////////////////////////// /////////////////////////

import UIKit
import AVFoundation

class SecondViewController: UIViewController {

var audioPlayer: AVAudioPlayer!

let notificationCenter = NotificationCenter.default
@IBOutlet weak var volumeSlider: UISlider!
@IBOutlet weak var volumeLabel: UILabel!
@IBAction func volumeChange(_ sender: UISlider)
{
    volumeLabel.text = String(Int(sender.value))
    volumeSlider.value = sender.value
    audioPlayer.volume = volumeSlider.value
    notificationCenter.post(name: NSNotification.Name(rawValue: "test"), object: nil)

    audioPlayer.play()
}

override func viewDidLoad()
{
    super.viewDidLoad()

    if let url=Bundle.main.url(forResource:"Alarm",withExtension:".mp3" )
    {

        do {
            audioPlayer = try AVAudioPlayer(contentsOf:url)
            audioPlayer?.play(atTime:1 * 10)

        }catch{
            audioPlayer = nil
        }
    }else{
        fatalError("Url is nil")
    }

}
extension Notification.Name
{
   static let myNotificationName = Notification.Name("test")
}

Answer 1

将NSNotificationCenter用于诸如此类的简单任务可能会过大。通常，您可以使用闭包来捕获组件或视图控制器中的数据更改。

在SecondViewController中创建一个包含闭包的变量：

var onVolumeChange: ((value: Float) -> Void)?

在IBAction中调用它，它监视滑块的onChange事件。

@IBAction func volumeChange(_ sender: UISlider)
{
    self.onVolumeChange?(sender.value)
}

在导航到第二个时，从onVolumeChange中传递FirstViewController闭包。我不确定您如何执行导航，所以我假设您以编程方式进行导航。

let vc = UIStoryboard(name: "main", bundle: nil).instantiateViewController(withIdentifier: "SecondViewController")
vc.onVolumeChange = { value in 
    audioPlayer.volume = value
}
self.navigationController?.pushViewController(vc, animated: true)

如何将SecondViewController上的UISlider值传递给FirstViewController上的Alarm？

1 个答案: