如何限制UITextView中的行数？-Java 学习之路

我的屏幕上有一个UITextView，用户应该只填充 two lines ，当用户在第二行时，返回键应该变为 Done .

如何在UITextView中限制 lines 的数量？我搜索了很多，没有结果有用！

我找到了Swift的答案：

locationNoteTextView.textContainer.maximumNumberOfLines = 2
self.locationNoteTextView.textContainer.lineBreakMode = NSLineBreakMode.ByClipping

它不起作用，通过这种方式用户可以输入无限字符，但在屏幕上查看的只是两行！

因此，如果您尝试打印textView文本，您将找到灾难文本 .

6 回答

你需要实现 textView:shouldChangeTextInRange:replacementText: . 只要文本要更改，就会调用此方法 . 您可以使用其text属性访问文本视图的当前内容 .

使用 [textView.text stringByReplacingCharactersInRange:range withString:replacementText] 从传递的范围和替换文本构造新内容 .

然后，您可以计算行数并返回 YES 以允许更改或 NO 拒绝它 .

EDIT: 关于OP请求：

func sizeOfString (string: String, constrainedToWidth width: Double, font: UIFont) -> CGSize {
    return (string as NSString).boundingRectWithSize(CGSize(width: width, height: DBL_MAX),
        options: NSStringDrawingOptions.UsesLineFragmentOrigin,
        attributes: [NSFontAttributeName: font],
        context: nil).size
}


func textView(textView: UITextView, shouldChangeTextInRange range: NSRange, replacementText text: String) -> Bool {
    let newText = (textView.text as NSString).stringByReplacingCharactersInRange(range, withString: text)
    var textWidth = CGRectGetWidth(UIEdgeInsetsInsetRect(textView.frame, textView.textContainerInset))
    textWidth -= 2.0 * textView.textContainer.lineFragmentPadding;

    let boundingRect = sizeOfString(newText, constrainedToWidth: Double(textWidth), font: textView.font!)
    let numberOfLines = boundingRect.height / textView.font!.lineHeight;

    return numberOfLines <= 2;
}

回复于 2024-04-26T15:21:05+08:00

-3

适用于iOS 7

textView.textContainer.maximumNumberOfLines = 10;
textView.textContainer.lineBreakMode = NSLineBreakByTruncatingTail;

要么

textView.textContainer.maximumNumberOfLines = 10;
[textView.layoutManager textContainerChangedGeometry:textView.textContainer];

回复于 2024-04-26T15:21:05+08:00

这是@Abhinav的回答，但在 Swift

func textView(textView: UITextView, shouldChangeTextInRange range: NSRange, replacementText text: String) -> Bool {


    let newText = (textView.text as NSString).stringByReplacingCharactersInRange(range, withString: text)

    let textAttributes = [NSFontAttributeName: textView.font]

    var textWidth: CGFloat = CGRectGetWidth(UIEdgeInsetsInsetRect(textView.frame, textView.textContainerInset))

    textWidth -= 2.0 * textView.textContainer.lineFragmentPadding

    let boundingRect: CGRect = newText.boundingRectWithSize(CGSizeMake(textWidth, 0), options: NSStringDrawingOptions.UsesLineFragmentOrigin|NSStringDrawingOptions.UsesFontLeading, attributes: textAttributes, context: nil)

  var numberOfLines = CGRectGetHeight(boundingRect) / textView.font.lineHeight;

    return numberOfLines <= 2;
}

回复于 2024-04-26T15:21:05+08:00

如果有人想要实时行数，这就是你用RxSwift和RxCocoa做的

let disposeBag = DisposeBag()

    textView.rx_text.asDriver().driveNext { text in

        let text = text as NSString

        var textWidth: CGFloat = CGRectGetWidth(UIEdgeInsetsInsetRect(self.textView.frame, self.textView.textContainerInset))

        textWidth -= 2.0 * self.textView.textContainer.lineFragmentPadding

        let textAttributes = [NSFontAttributeName: UIFont(name: “Set your font here”, size: 26.0)!]

        let boundingRect: CGRect = text.boundingRectWithSize(CGSizeMake(textWidth, 0), options: [NSStringDrawingOptions.UsesLineFragmentOrigin, NSStringDrawingOptions.UsesFontLeading], attributes: textAttributes, context: nil)

        let font = UIFont(name: “Set your font here”, size: 26.0)

        guard let lineHeight = font?.lineHeight else {return}

        let numberOfLines = CGRectGetHeight(boundingRect) / lineHeight

        if numberOfLines <= 2 {


            self.textView.typingAttributes = [NSFontAttributeName: UIFont(name: “Set your font here”, size: 26.0)!, NSForegroundColorAttributeName: “Set your color here”]

        } else {

            self.textView.typingAttributes = [NSFontAttributeName: UIFont(name: “Set your font here”, size: 18.0)!, NSForegroundColorAttributeName: “Set your color here”]

        }

    }.addDisposableTo(disposeBag)

回复于 2024-04-26T15:21:05+08:00

这是@ Abhinav的回答更新 Swift 3

func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {

    guard maxLines > 0 else {
        return true
    }

    let newText = (textView.text as NSString).replacingCharacters(in: range, with: text)

    let textAttributes = [NSAttributedStringKey.font : textView.font!]

    var textWidth: CGFloat = UIEdgeInsetsInsetRect(textView.frame, textView.textContainerInset).width

    textWidth -= 2.0 * textView.textContainer.lineFragmentPadding

    let boundingRect: CGRect = newText.boundingRect(with: CGSize(width: textWidth, height: 0), options: [.usesLineFragmentOrigin, .usesFontLeading], attributes: textAttributes, context: nil)

    let numberOfLines = Int(floor(boundingRect.height / textView.font!.lineHeight))

    return numberOfLines <= maxLines

}

其中 maxLines 是您要将textView限制为的行数 . 如果它是0那么无限数量的行 .

回复于 2024-04-26T15:21:05+08:00

在下面找到Abhinav答案的Objective C版本：

-(BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text
{
    NSString *newText = [textView.text stringByReplacingCharactersInRange:range withString:text];
    CGFloat textWidth = CGRectGetWidth(UIEdgeInsetsInsetRect(textView.frame, textView.textContainerInset));
    textWidth -= 2.0 * textView.textContainer.lineFragmentPadding;

    CGSize boundingRect = [self sizeOfString:newText constrainedToWidth:textWidth font:textView.font];
    NSInteger numberOfLines = boundingRect.height / textView.font.lineHeight;

    return numberOfLines <= 2;
}

-(CGSize)sizeOfString:(NSString *)string constrainedToWidth:(double)width font:(UIFont *)font
{
    return  [string boundingRectWithSize:CGSizeMake(width, DBL_MAX) options:NSStringDrawingUsesLineFragmentOrigin attributes:@{NSFontAttributeName: font} context:nil].size;
}

回复于 2024-04-26T15:21:05+08:00

如何限制UITextView中的行数？

6 回答

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