How to put iPhone UIDatePicker into 24 HR mode without affecting other apps?

My users was to select their times using the 24 HR clock instead of the AM/PM 12 hour clock in my iPhone app. Presently, as far as I can tell, the only way to put the UIDatePicker into 24 HR time mode is from the device's settings. My users only want 24 HR mode for this app, not their e开发者_JAVA技巧ntire device.

Does anyone know a way to put the UIDatePicker into 24 HR clock mode for my app only?

Thank you.

P.S. Would it be possible when my app starts it would put the device into 24 HR mode and then when the app goes to the background or closes it sets the device settings back to the way it was? I wonder if the app can control the device settings while it's used?

It can't be done, hopefully this will be available in the future. I created my own date/time input to make this possible via a UITextField.