I like to replicate the form behavior of Safari on the iPhone in my own app. If you enter data in an web form you get a separate UIToolbar (previous, next, done) just above
I'm looking for the solution for this issue too.
I found this was the best solution, you can use this SCKit to add tool bar to dismiss the UIPickerView or the UIDatePicker as you want.
Following is github link: https://github.com/scelis/SCKit/tree/
Have fun!