ios - 如何自动滚动 UITableView 单元格

Question

如何自动滚动 UITableView 的单元格。
嗯，我觉得很容易实现，而且我做到了这么近

This is my SPEECH function in ViewController below

var myUtterance = AVSpeechUtterance(string: "")
let speecher = AVSpeechSynthesizer()
func speechWord(word: String){
    DispatchQueue.main.async {
        self.speecher.stopSpeaking(at: AVSpeechBoundary.immediate)
        self.myUtterance = AVSpeechUtterance(string: word)
        self.myUtterance.voice = AVSpeechSynthesisVoice(language: "en-US")
        self.myUtterance.rate = 0.5
        self.speecher.speak(self.myUtterance)
    }
}

This is my AutoSpeech function in ViewController below

func startAutoSpeechList(row: Int){
    let indexPath = IndexPath(row: row, section: 0)
    print(indexPath)
    myTableView.selectRow(at: indexPath, animated: true, scrollPosition: .top) //Select
    myTableView.scrollToNearestSelectedRow(at: .top, animated: true) //Scroll
    let cell = tableView(myTableView, cellForRowAt: indexPath) as! WordTableViewCell
    self.speechWord(word: cell.spell.text!) //Speech
}

(Method 1) This is The Button I use to activate The AutoSpeech function

var row = 0
@IBAction func myAutoButton(_ sender: UIBarButtonItem) {
    self.startAutoSpeechList(row: row)
    row += 1
}

方法一，看我上传的图片 当我第一次点击 AutoButton 时，它跳转到屏幕 A。我再次点击 AutoSpeech 按钮，它跳转到屏幕 B。然后我点击 AutoButton第三次，跳转到屏幕C。

(Method 2) This is The Button I use to activate The AutoSpeech function

@IBAction func myAutoButton(_ sender: UIBarButtonItem) {
    for myRow in 0..<3{
        self.startAutoSpeechList(row: myRow)
    }
}

方法 2， 当我单击 AutoSpeech 按钮时，它会立即跳转到屏幕 C，而不会在屏幕 A、B 停留任何时间。你能解释一下为什么它会立即逃离屏幕 A、B 吗？

Is there Method 3 to help me achieve that When I click AutoSpeech Button, it will jump to Screen A and pronounce the word "cat", then jump to B after finishing the pronunciation and pronounce "dog", then jump to C, and so on.... Who can help me to achieve Method 3? Swift 4 will be better for me.

Answer 1

您的方法 2 代码是您所需要的，但是它会连续运行并在几毫秒内完成。

可用的最佳选择是使用 AVSpeechSynthesizerDelegate监控方法确实讲完了。

在你的情况下你可以使用

func speechSynthesizer(AVSpeechSynthesizer, didFinish: AVSpeechUtterance)

在当前播放的语音结束播放时收到通知。一旦它被调用，你就可以调用一个函数，比如 speakNextRow 或者其他的东西来移动到列表中的下一个。

粗略地说，这是您应该考虑做的事情。 (未在 xcode 中测试，用作如何执行所需操作的指南)。

class ViewController: UIViewController, AVSpeechSynthesizerDelegate {

    var currentSelectedRow: Int?
    var isAutoPlaying = false

    var myUtterance = AVSpeechUtterance(string: "")
    let speecher = AVSpeechSynthesizer()

    override func viewDidLoad() {
       super.viewDidLoad()

       self.speecher.delegate = self
    }

    func speechWord(word: String){

        DispatchQueue.main.async {
            self.speecher.stopSpeaking(at: AVSpeechBoundary.immediate)
            self.myUtterance = AVSpeechUtterance(string: word)
            self.myUtterance.voice = AVSpeechSynthesisVoice(language: "en-US")
            self.myUtterance.rate = 0.5
            self.speecher.speak(self.myUtterance)
        }
    }

    func startAutoPlay() {
        isAutoPlaying = true
        currentSelectedRow = 0
        scrollToAndSpeak(at: currentSelectedRow)
    }

    func scrollToAndSpeak(at index: Int) {
        // make sure to check not going out of bounds!!
        let indexPath = IndexPath(row: index, section: 0)
        myTableView.selectRow(at: indexPath, animated: true, scrollPosition: .top) //Select
        myTableView.scrollToNearestSelectedRow(at: .top, animated: true) //Scroll
        let cell = tableView(myTableView, cellForRowAt: indexPath) as! WordTableViewCell
        self.speechWord(word: cell.spell.text!) //Speech
    }

    func speechSynthesizer(AVSpeechSynthesizer, didFinish: AVSpeechUtterance) {
         if isAutoPlaying {
              // make sure to check not going out of bounds!!
              currentSelectedRow = (currentSelectedRow ?? 0) + 1
              scrollToAndSpeak(at: currentSelectedRow)
         }
    }
}

因此，当您选择自动播放时，将标志 isAutoPlaying 设置为 true 并开始播放第一个。完成后，代表将收到通知，我们会增加索引并开始播放下一个，依此类推，直到用户取消它或我们用完单元格。