UITextView 打字动画

Question

我有一个具有固定宽度和高度的

uitextview

。

为了使文本更容易理解，我想执行逐个字符的输入“动画”，并且能够使用

Timer

对象使其工作。

我唯一的问题是......当输入的第一个字符会溢出到下一行时，它不会在下一行输入第一个字符，而是在当前行输入。当输入到达

uitextview

末尾时，该单词之前输入的所有字符才会被带到下一行。

这会导致打字动画不稳定，我想知道是否可以通过提前在新行上输入第一个字符来使其变得更流畅。任何指导将不胜感激！

这是我当前的功能：

func type(text: String) {

    let paragraphStyle = NSMutableParagraphStyle()
    paragraphStyle.alignment = .center
    paragraphStyle.lineBreakMode = .byWordWrapping
    paragraphStyle.paragraphSpacing = 10

    let bodyAttributes = [
        NSAttributedString.Key.foregroundColor: UIColor.black,
        NSAttributedString.Key.paragraphStyle: paragraphStyle,
        NSAttributedString.Key.font: UIFont.systemFont(ofSize: 17)
    ]

    let characters = Array(text)
    var characterIndex = 0

    let attributedString = NSMutableAttributedString()

    Timer.scheduledTimer(withTimeInterval: 0.05, repeats: true) { [weak self] timer in
        guard let self = self else { return }

        while characters[characterIndex] == " " {
            attributedString.append(NSAttributedString(string: " ", attributes: bodyAttributes))
            textView.attributedText = attributedString

            characterIndex += 1

            if characterIndex == characters.count {
                timer.invalidate()
                return
            }
        }

        let char = String(characters[characterIndex])
       
            attributedString.append(NSAttributedString(string: char, attributes: bodyAttributes))
        
        textView.attributedText = attributedString

        characterIndex += 1

        if characterIndex == characters.count {
            timer.invalidate()
        }
    }
}

Answer 1

    func type(text: String, into textView: UITextView) {
let paragraphStyle = NSMutableParagraphStyle()
paragraphStyle.alignment = .center
paragraphStyle.lineBreakMode = .byWordWrapping
paragraphStyle.paragraphSpacing = 10

let bodyAttributes: [NSAttributedString.Key: Any] = [
    .foregroundColor: UIColor.black,
    .paragraphStyle: paragraphStyle,
    .font: UIFont.systemFont(ofSize: 17)
]

var characterIndex = 0
var currentLine = 0
var currentLineLength = 0
let words = text.components(separatedBy: .whitespaces)

Timer.scheduledTimer(withTimeInterval: 0.05, repeats: true) { timer in
    guard characterIndex < text.count else {
        timer.invalidate()
        return
    }

    let char = String(text[text.index(text.startIndex, offsetBy: characterIndex)])
    let attributedString = NSMutableAttributedString(attributedString: textView.attributedText ?? NSAttributedString())

    if char == " " {
        attributedString.append(NSAttributedString(string: " ", attributes: bodyAttributes))
        textView.attributedText = attributedString
        characterIndex += 1
        currentLineLength += 1
    } else {
        if currentLineLength >= textView.frame.width / textView.font!.pointSize {
            currentLine += 1
            attributedString.append(NSAttributedString(string: "\n", attributes: bodyAttributes))
            textView.attributedText = attributedString
            currentLineLength = 0
        }

        attributedString.append(NSAttributedString(string: char, attributes: bodyAttributes))
        textView.attributedText = attributedString
        characterIndex += 1
        currentLineLength += 1
    }
}

}

在这

• 我添加了一个新的 currentLine 变量来跟踪当前行。
• 我更新了周期时间以使其正常工作。现在空间被添加一次，循环继续，直到找到可用空间指针。
• 我添加了逻辑来在添加字符之前检查当前行是否比 UITextView 的宽度长。如果是这样，则扩展换行符指针并将当前的 LineLength 重置为 0。
• 我还添加了一个事件，用于在覆盖计时器之前检查 Index 属性是否已到达文本文件的末尾。