PresentModalViewController on IPhone applications

i have an application with many views ( about 20 view ) these views are开发者_如何学Python populated using (PresendModalViewController), and populated in a number of times through a loop ( let's say that 1,2,3,4,5...20 then 1,2,3,4....20 an so for) my question is , shall i dismiss the previous view each time i populated the next one?

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why not see this

for(int i=1;i<=20;i++)
{
   if(i>1)
    [self.navigationController dismissModelViewControllerAnimated:YES];
   [self.navigationController presentViewController:youobj animated:YES];
}