如何停止NSTextView显示指定字体中不支持的字符

import Cocoa

func removeUnsupportedCharacters(textView: NSTextView, font: NSFont) {
    guard let textStorage = textView.textStorage else {
        return
    }
    
    let fullRange = NSRange(location: 0, length: textStorage.length)
    let unsupportedCharacterSet = font.coveredCharacterSet.inverted
    
    textStorage.beginEditing()
    textStorage.enumerateAttribute(.font, in: fullRange, options: []) { (value, range, _) in
        guard let attributeFont = value as? NSFont else {
            return
        }
        
        if attributeFont != font {
            return
        }
        
        let attributedSubstring = textStorage.attributedSubstring(from: range)
        let string = attributedSubstring.string
        
        var modifiedString = ""
        for scalar in string.unicodeScalars {
            if unsupportedCharacterSet.contains(scalar) {
                // 可以选择删除、替换或者忽略不支持的字符
                // 这里示例选择删除不支持的字符
                continue
            }
            modifiedString.append(Character(scalar))
        }
        
        textStorage.replaceCharacters(in: range, with: modifiedString)
    }
    textStorage.endEditing()
}

// 使用示例
let textView = NSTextView(frame: NSRect(x: 0, y: 0, width: 200, height: 100))
let font = NSFont.systemFont(ofSize: 12)
textView.font = font
textView.string = "Hello, 世界! 🌍"

removeUnsupportedCharacters(textView: textView, font: font)

print(textView.string) // 输出：Hello, 世界!