initwithstyle:reuseIdentifier: not called
If your cell is being created from a storyboard prototype (which you have declared as the custom class in IB) then it won't be created with initWithStyle... but initWithCoder: instead, like any other object loaded from a nib. If you have any setup code, it should be in there or in awakeFromNib.
With the storyboard involved, everything changes. This is the method that gets called.
-(id)initWithCoder:(NSCoder *)aDecoder {
if ( !(self = [super initWithCoder:aDecoder]) ) return nil;
// Your code goes here!
return self;
}