文本显示在模拟器中但不在iPhone上显示

Question

我已编码此代码：

let info_centill: UITextView = {
    let tv = UITextView()
    tv.text = "Connecting people with similar hobbies and interests around the world!"
    tv.font = UIFont(name: "ZonaPro", size: 20)
    tv.textColor = .lightGray
    tv.textAlignment = .center
    tv.frame = CGRect(x:0,y:30,width:0,height:0)
    tv.backgroundColor = .gray

    let fixedWidth = tv.frame.size.width
    tv.sizeThatFits(CGSize(width: fixedWidth, height: CGFloat.greatestFiniteMagnitude))

    let newSize = tv.sizeThatFits(CGSize(width: fixedWidth, height: CGFloat.greatestFiniteMagnitude))
    var newFrame = tv.frame
    newFrame.size = CGSize(width: max(newSize.width, fixedWidth), height: newSize.height)
    tv.frame = newFrame

    return tv
}()

info_centill.layoutIfNeeded()        
info_centill.topAnchor.constraint(equalTo: view.topAnchor,constant: 120).isActive = true
info_centill.leftAnchor.constraint(equalTo: view.leftAnchor).isActive = true
info_centill.rightAnchor.constraint(equalTo: view.rightAnchor).isActive = true

当我运行此代码时，我在模拟器中得到了这个结果：

但在iPhone上我只能得到没有文字的灰色背景。问题是什么？我应该相信哪一个？