Ios 在swift中设置UITextfield占位符的字体

我使用以下代码为UITextfield的文本（16）和占位符（9）设置不同的字体

字体大小设置正确，但占位符文本在文本字段中设置得稍高

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如何解决此问题？有什么建议吗？

我通过编程解决了这个问题，因为我找不到任何其他方法来解决它

代码如下：

class ViewController: UIViewController {

    @IBOutlet weak var textField: UITextField!
    var placeholder : UILabel!

    override func viewDidLoad() {
        super.viewDidLoad()

        placeholder = UILabel(frame: CGRect( x: 0, y: 0, width: textField.bounds.width, height: textField.bounds.height))
        placeholder.text = "Search String be in meddle left"
        placeholder.font = UIFont.italicSystemFontOfSize(9)
        placeholder.textColor = UIColor.grayColor()
        placeholder.hidden = !textField.text!.isEmpty
        placeholder.textAlignment = .Center
        textField.addSubview(placeholder)
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }

    @IBAction func textField_EditingChanged(sender: AnyObject) {
        placeholder.hidden = !textField.text!.isEmpty
    }
} 

class ViewController: UIViewController {

    @IBOutlet weak var textField: UITextField!
    var placeholder : UILabel!

    override func viewDidLoad() {
        super.viewDidLoad()

        placeholder = UILabel(frame: CGRect( x: 0, y: 0, width: textField.bounds.width, height: textField.bounds.height))
        placeholder.text = "Search String be in meddle left"
        placeholder.font = UIFont.italicSystemFontOfSize(9)
        placeholder.textColor = UIColor.grayColor()
        placeholder.hidden = !textField.text!.isEmpty
        placeholder.textAlignment = .Center
        textField.addSubview(placeholder)
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }

    @IBAction func textField_EditingChanged(sender: AnyObject) {
        placeholder.hidden = !textField.text!.isEmpty
    }
}