Keyboard hidden a TextField in IOS

Hi, i have a problem in IOS:

if i have three TextField box and when i click in the lower then keyboard show and the TextField is hidden. Only in IOS, in Android the window goes up.

What can i do??

Thanks

<Label id="LtxtNSerie" top="12%">Nº Serie</Label>
    <TextField id="TNSerie" top="18%" height="8%" width="80%" maxLength="12"/>
<Label id="LtxtPin" top="32%">PIN</Label>
    <TextField id="TPin" top="38%" height="8%" width="80%" maxLength="6"/>
<Label id="LtxtNombre" top="52%">Nombre</Label>
    <TextField id="TNombre" top="58%" height="8%" width="80%" maxLength="24"/>