swift修改UITextfield的Placeholder字体

**//第一种 **

let textField = UITextField.init()  
textField.placeholder = placehold  
//字体大小  
textField.setValue(UIFont.systemFont(ofSize: 15),forKeyPath: "_placeholderLabel.font")  
//字体颜色  
textField.setValue(UIFont.systemFont(ofSize: 15), forKeyPath: "_placeholderLabel.textColor")

//第二种

//字体大小  
textField.attributedPlaceholder = NSAttributedString.init(string:"输入你需要的服务", attributes: [NSFontAttributeName:UIFont.systemFont(ofSize:15)])  
//字体颜色  
textField.attributedPlaceholder = NSAttributedString.init(string:"输入你需要的服务", attributes: [  NSForegroundColorAttributeName:UIColor.red])