UILabel不会使用计时器更新

import UIKit

class ViewController: UIViewController {
    @IBOutlet weak var label: UILabel!
    var timer: Timer?
    var count = 0
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        label.text = "0"
        
        timer = Timer.scheduledTimer(withTimeInterval: 1.0, repeats: true) { [weak self] (_) in
            self?.count += 1
            self?.label.text = "\(self?.count ?? 0)"
        }
        
        RunLoop.current.add(timer!, forMode: .common)
    }
}