If you want a datepicker to be presented while clicking the textfield, you can directly present the datepicker. Make the datepicker as your textfield's inputview.
pickerView = [[UIDatePicker alloc] initWithFrame:CGRectMake(0, 40, 320, 216)];
//Configure picker...
[pickerView setMinuteInterval:5];
[pickerView setDatePickerMode:UIDatePickerModeTime];
[dateTextField setInputView:pickerView];