UIAlertView修改键盘颜色

用到LoginAndPasswordInput的UIAlertView

[message setAlertViewStyle:UIAlertViewStyleLoginAndPasswordInput];

alertview 的颜色是标准的蓝色，但是弹出的键盘颜色是黑色，我想修改，怎么改？

使用UITextfield 的keyboardAppearance 属性来设置

typedef NS_ENUM(NSInteger, UIKeyboardAppearance) {
    UIKeyboardAppearanceDefault, // Default apperance for the current input method.
    UIKeyboardAppearanceAlert  // Appearance suitable for use in "alert" scenarios.
};


textfield.keyboardAppearance = UIKeyboardAppearanceDefault;