ios - set uidatepicker date from string -

Question: Renewed question:

I have an application where the user can add a new workshop along with a workshop date. After that, he chooses from a UIDatePicker After this, the user can edit the workshop information including editing. The following is what I am trying to do: 1. When the user adds a new workshop, read the time to select the user from UIDatePicker . 2. Convert date to string and save it to database. 3. When the user wants to edit the workshop, I should get the workshop date from the database and change it from string to NSDate . 4. UIDatePicker is built in "interface" in NSDate .

I think this sound is logical. However, this is not working for me and I'm not sure why the code is here:

In the AddWorkshop.m class

  NSDateFormatter * dateFormat = [[NSDateFormatter alloc] init]; [DateFormat setDateStyle: NSDateFormatterMediumStyle]; // WSDate a NSString variable self.WSDate = [dateFormat stringFromDate: [sender date]];  

In the EditWorkshop.m category

  NSDateFormatter * df = [[NSDateFormatter alloc] init]; [DF Settte Stella: NSDAT Formamium Style]; NSDate * date1 = [df dateFromString: self.WSDate]; [Self-portrait picture set date: date 1];  

The problem is:

1. UIDatePicker will not change the date The specified date, It always shows on today's date.

2. When I have the NSLOG date 1 and myself If I try WDDate, the value of date 1 is always one day low then self.WSDate

3. [UIDTPK set date: NSDT] has a specific format for the date passed? For example: Is it ok to have "MMMM DD Yay" or "MMD-DD-YEY" or any format?