float x,y;
    float space =  kSpacing;
    float width = rect.size.width;
    int ct = [_images count];        
    float totalspace = (ct-1)*space;
    
    x= (width/2) - (totalspace/2);//find the starting CENTER of first point
    y = rect.size.height/2;
    
    for (UIImage *img in _images) {
        CGSize sz = img.size;
        CGPoint pt = CGPointMake(x - sz.width/2, y - sz.height/2);
        NSLog(@"pt: %@",NSStringFromCGPoint(pt));
        [img drawAtPoint:pt];
        x+=space;
    }

equal horizontal distribution

Objective C