限制 UITextField 和 UITextView 的输入

demo.swift

import UIKit
import IQKeyboardManager

/// 语音播报
class SecurityActionVoiceContentViewController: UIViewController {
    lazy var textView = IQTextView().do {
        $0.font = .systemFont(ofSize: 15)
        $0.textColor = UIColor(hexString: "#333333")
        $0.backgroundColor = .white
        $0.layer.cornerRadius = 10
    }

    lazy var tipsLabel = UILabel().do {
        $0.font = .systemFont(ofSize: 14)
        $0.textColor = UIColor(hexString: "#333333")
        $0.text = L10n("security.config.action.voice.tips")
    }

    lazy var countLabel = UILabel().do {
        $0.font = .systemFont(ofSize: 14)
        $0.textColor = UIColor(hexString: "#333333")
    }

    // 最大字符数
    let maxCharsCount = 200

    var textLimitDelegate: TextInputLimitDelegate?

    var text: String!
    var completion: ((String) -> Void)?
    convenience init(text: String, completion: ((String) -> Void)?) {
        self.init(nibName: nil, bundle: nil)
        self.text = text
        self.completion = completion
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        title = L10n("Localizable_LinkageOutPut_Voice")
        view.backgroundColor = UIColor(hexString: "#F5F5F8")
        navigationItem.rightBarButtonItem = UIBarButtonItem(title: L10n("Save"), style: .plain, target: self, action: #selector(saveAction))

        setupViews()

        textView.text = text
        textView.placeholder = L10n("security.config.action.voice.placeholder")
        textView.placeholderTextColor = .lightGray

        textLimitDelegate = TextInputLimitDelegate(allowedRegular: TextInputLimitDelegate.nameRex,
                                                   maxLength: 200, textChanged: { [weak self] text in
                                                       self?.updateTextCount(text)
                                                   })
        textLimitDelegate?.setInputView(textView)

        updateTextCount(text)
    }

    @objc func saveAction() {
        textView.resignFirstResponder()
        completion?(textView.text)
    }

    func updateTextCount(_ text: String?) {
        countLabel.text = "\(text?.lengthInBytes() ?? 0)/\(200)"
    }

    func setupViews() {
        view.addSubview(textView)
        view.addSubview(tipsLabel)
        view.addSubview(countLabel)

        textView.layout { [
            $0.topAnchor.equalTo(view.safeAreaLayoutGuide.topAnchor).offset(10),
            $0.leadingAnchor.equalTo(view.leadingAnchor).offset(20),
            $0.trailingAnchor.equalTo(view.trailingAnchor).offset(-20),
            $0.heightAnchor.equal(160),
        ] }

        tipsLabel.layout { [
            $0.topAnchor.equalTo(textView.bottomAnchor).offset(10),
            $0.leadingAnchor.equalTo(textView.leadingAnchor),
        ] }

        countLabel.layout { [
            $0.topAnchor.equalTo(textView.bottomAnchor).offset(10),
            $0.trailingAnchor.equalTo(textView.trailingAnchor),
        ] }
    }

    override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
        super.touchesEnded(touches, with: event)
        textView.resignFirstResponder()
    }
}

TextInputLimitDelegate.swift

extension String {
    /// 计算字节数，中文算非ASCII字符，占2个字节
    func lengthInBytes() -> Int {
        var length = 0
        for char in self {
            if char.isASCII {
                length += 1
            } else {
                length += 2
            }
        }
        return length
    }

    func removeEmoji() -> String {
        self.filter {
            $0.unicodeScalars.allSatisfy({ scalar in
                !scalar.properties.isEmojiPresentation
            })
        }
    }

    var containEmoji: Bool {
        unicodeScalars.contains { scalar in
            scalar.properties.isEmojiPresentation
        }
    }
}

/// 文本输入限制
@objc
public class TextInputLimitDelegate: NSObject, UITextFieldDelegate, UITextViewDelegate {
    // 中英文 + 数字 + 空格
    @objc static let nameRex = "[a-zA-Z0-9\\u4E00-\\u9FA5\\s]"
    // 纯数字
    @objc static let phoneNumberRex = "^[0-9]+$"

    // 文本变化
    @objc var textChanged: ((String?) -> Void)?
    // 最大长度，0为不限制（计算字节数，中文算非ASCII字符，占2个字节）
    @objc var maxLength: UInt = 0
    // 允许输入的正则表达式
    @objc var allowedRegular: String = ""
    // 是否允许换行，针对 UITextView
    @objc var allowLineBreak = false

    @objc convenience init(allowedRegular: String, maxLength: UInt, textChanged: ((String?) -> Void)?) {
        self.init()
        self.allowedRegular = allowedRegular
        self.maxLength = maxLength
        self.textChanged = textChanged
    }

    @objc func setInputView(_ inputView: UIView) {
        switch inputView {
        case let textField as UITextField:
            textField.delegate = self
            textField.addTarget(self, action: #selector(textFieldChangedText(_:)), for: .editingChanged)
        case let textView as UITextView:
            textView.delegate = self
        default:
            break
        }
    }

    private override init() {
        super.init()
    }

    func inputView(_ inpuText: String?, textInputMode: UITextInputMode?, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
        // 删除按钮点击
        if text.isEmpty {
            return true
        }

        // 禁止 emoji 输入
        guard let language = textInputMode?.primaryLanguage,
              language != "emoji" else {
            return false
        }

        // 如果是中文输入法，九宫格输入法的 A-Z 字母点击时，预览会显示➋这样的占位符，此时用户还没有真正的选择
        // 如果输入 "ma"，updatedText 会是 "m➋"
        let nineChars = "➋➌➍➎➏➐➑➒"
        if text.contains(where: { nineChars.contains($0) }) {
            return true
        }

        // 包含 emoji
        if text.containEmoji {
            return false
        }

        // 正则为空就不判断了
        if allowedRegular.isEmpty {
            return true
        }

        return validateInput(regexPattern: allowedRegular, inputString: text)
    }

    // 验证输入的字符串是否符合正则表达式
    func validateInput(regexPattern: String, inputString: String) -> Bool {
        do {
            let regex = try NSRegularExpression(pattern: regexPattern, options: .caseInsensitive)
            let range = NSRange(location: 0, length: inputString.count)
            let matches = regex.matches(in: inputString, options: [], range: range)
            return matches.count > 0
        } catch {
            print("Invalid regex pattern: \(error)")
            return false
        }
    }

    // 限制输入长度
    func changedText(_ text: String?) -> String {
        guard var text else { return "" }

        Logger.debug("输入: \(text)")

        if !allowLineBreak {
            // 禁止换行
            text = text.replacingOccurrences(of: "\n", with: "")
        }

        while (text.lengthInBytes() > maxLength) {
            text.removeLast()
        }

        return text
    }

    // 编辑结束的时候，将首尾的空白去掉
    func trimText(_ text: String?) -> String {
        guard let text else { return "" }

        return text.trimmingCharacters(in: .whitespacesAndNewlines)
    }

    // MARK: UITextFieldDelegate

    public func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
        if (!textField.isFirstResponder) {
            return true
        }

        return inputView(textField.text, textInputMode: textField.textInputMode, shouldChangeTextIn: range, replacementText: string)
    }

    @objc func textFieldChangedText(_ textField: UITextField) {
        textField.text = changedText(textField.text)
        textChanged?(textField.text)
    }

    public func textFieldDidEndEditing(_ textField: UITextField) {
        textField.text = trimText(textField.text)
        textChanged?(textField.text)
    }

    public func textFieldShouldReturn(_ textField: UITextField) -> Bool {
        textField.resignFirstResponder()
        return true
    }

    // MARK: UITextViewDelegate

    public func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
        inputView(textView.text, textInputMode: textView.textInputMode, shouldChangeTextIn: range, replacementText: text)
    }

    public func textViewDidChange(_ textView: UITextView) {
        textView.text = changedText(textView.text)
        textChanged?(textView.text)
    }

    public func textViewDidEndEditing(_ textView: UITextView) {
        textView.text = trimText(textView.text)
        textChanged?(textView.text)
    }
}