Obj c - Parse Issue on if statement

Im getting a 'parse issue: Expected expression' error on the 'else if' line and can't work out why, any help would be appreciated.

Thanks

if (sender == self.slider)
    self.textField.text = string;
NSString* string2 = [NSString stringWithFormat:@"%f", (440 * pow(2, (sender.value-69.0)/12.0))];
    self.textField2.text = string2;

else if (sender == self.slider2)
   self.textField2.text = string;
string2 = [NSString stringWithFormat:@"%f", (log2f (sender.value / 440) * 12) + 69]; 
self.textField.text = string2;