根据内容长度修改NSTextField的字体大小

import Cocoa

class ViewController: NSViewController {
    @IBOutlet weak var textField: NSTextField!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 监听文本内容变化
        NotificationCenter.default.addObserver(self, selector: #selector(textFieldDidChange(_:)), name: NSControl.textDidChangeNotification, object: textField)
    }
    
    @objc func textFieldDidChange(_ notification: Notification) {
        if let textField = notification.object as? NSTextField {
            let contentLength = textField.stringValue.count
            let threshold = 10 // 阈值，可根据实际情况调整
            
            // 根据文本长度调整字体大小
            if contentLength > threshold {
                textField.font = NSFont.systemFont(ofSize: 12) // 减小字体大小
            } else {
                textField.font = NSFont.systemFont(ofSize: 16) // 增大字体大小
            }
        }
    }
}