Put some UILabels above each other and react on dynamic sizes in iPhone

I'm starting with iPhone programming. I have a navigationcontroller, to which I push an new view. For this new view I created a new viewcontroller class with XIB file. in Interface Builder I added some UILabels above each other, showing informations. the content of the uilabels is defined during runtime, the size should be dynamic. right now I do a

[label1 sizeToFit];

and the dynamic content is shown!

BUT: all labels which were beyond the label1 with the newly added text are now covered by this text. How could I manage them to just move down a bit so that they don't overlap with the label1? Fo I have to do this programmat开发者_JS百科ically?