Objective-c power operator not clear

Objective-c power operator not clear

Im working on a small calculation app and im using a formula i created in
PHP and now trying to translate to objective-c however, the power operator
is not clear to me.
Im looking at the following code:
float value = ((((x)*i)/12)/(1-(1+i/12)^-((x*12))))-i;
The poweroperator is non existand in Xcode.
How should i apply the power operator in xcode and could some assist me by
telling me where it should be?
Thanks in advance!