Question

我的屏幕上有一个UITextView，用户应该只填充两行，当第二行中的用户返回键应该变为完成。

如何在UITextView中限制行的数量？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，但在屏幕上查看的内容只有两行！

因此，如果您尝试打印textView文本，您将找到灾难文本。

Answer 1

您需要实施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拒绝更改。

编辑：在OP请求中：

<强>夫特：

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;
}

<强>的OBJ-C

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

- (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 andFont:textView.font];
    int numberOfLines = boundingRect.height / textView.font.lineHeight;
    return numberOfLines <= 2;
}

Answer 2

适用于iOS 7 +

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

OR

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

Answer 3

如果有人想要实时行号计数，这就是你用RxSwift＆amp; RxCocoa

    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)

Answer 4

这是@Abhinav的答案，但是在 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;
}

Answer 5

这是@ Abhinav的答案更新 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。

Answer 6

我将@Abhinav代码更新为Swift 5，还增加了对限制字符数的支持。

import UIKit

class ViewController: UIViewController {
    @IBOutlet private var textView: UITextView!

    private let maxNumberOfLines = 4
    private let maxCharactersCount = 100

    override func viewDidLoad() {
        super.viewDidLoad()
        textView.delegate = self
    }
}

extension ViewController: UITextViewDelegate {
    private func textView(_ textView: UITextView, newText: String, underLineLimit: Int) -> Bool {
        guard let textViewFont = textView.font else {
            return false
        }

        let rect = textView.frame.inset(by: textView.textContainerInset)
        let textWidth = rect.width - 2.0 * textView.textContainer.lineFragmentPadding

        let boundingRect = newText.size(constrainedToWidth: textWidth,
                                        font: textViewFont)

        let numberOfLines = boundingRect.height / textViewFont.lineHeight

        let underLimit = Int(numberOfLines) <= underLineLimit
        return underLimit
    }

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

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

        let underLineLimit = self.textView(textView, newText: newText, underLineLimit: maxNumberOfLines)
        let underCharacterLimit = newText.count <= maxCharactersCount
        return underLineLimit && underCharacterLimit
    }
}

extension String {
    func replacingCharacters(in range: NSRange, with string: String) -> String {
        let currentNSString = self as NSString
        return currentNSString.replacingCharacters(in: range, with: string)
    }

    func size(constrainedToWidth width: CGFloat, font: UIFont) -> CGSize {
        let nsString = self as NSString
        let boundingSize = CGSize(width: width, height: .greatestFiniteMagnitude)
        return nsString
            .boundingRect(with: boundingSize,
                          options: .usesLineFragmentOrigin,
                          attributes: [.font: font],
                          context: nil)
            .size
    }
}

Answer 7

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;
}

如何限制UITextView中的行数？

7 个答案: