Path 2.0 xcode menu animation

I downloaded Menu Path 2.0 from https://github.com/yourabi/PathMenuExample/downloads . The Add button allows you to expand and collapse an array of menu items (animated menu drawn along a curve).

But I want these buttons to expand / collapse in a straight line.

Here is the code for ExpandableNavigation.m:

- (void) expand {
transition = YES;

[UIView animateWithDuration:self.speed animations:^{
    self.mainButton.transform = CGAffineTransformMakeRotation( 45.0 * M_PI/180 );
}];

for (UIView* view in self.menuItems) {
    int index = [self.menuItems indexOfObject:view];
    CGFloat oneOverCount = self.menuItems.count + 50<=1?1.0:(1.0/(self.menuItems.count-1));
    CGFloat indexOverCount = index *oneOverCount;
    CGFloat rad =(1.0 - indexOverCount) * 90.0 * M_PI/180;
    CGAffineTransform rotation = CGAffineTransformMakeRotation( rad ) ;
    CGFloat x = (self.radius + self.bounce * self.radius ) * rotation.a;
    CGFloat y = (self.radius + self.bounce * self.radius ) * rotation.c;        

    CGPoint center = CGPointMake( view.center.x + x , view.center.y + y);