I also needed a HTML select-like control (single-selection dropdown list) without breaking the XCode legacy GUI interface across past and future iOS releases.
I ended up coding DownPicker, a lightweight control which does just that combining UITextField and UIPickerView. It can be used either as custom control (UIDownPicker) or also as control wrapper, upgrading any existing UITextField.
Here's how it looks like:

For more info and download you can check this brief tutorial or the GitHub project page (both wrote by me - the project is open-source).