iphone - UIScrollView Subview Scaling -

i'm attempting scale uiscrollview's subviews, based off of how far away center of container. think i'm close, isn't quite right. views left of center line scaled bit less right.

-(void)scrollviewdidscroll:(uiscrollview *)scrollview {     for( unsigned int i=0; i<[scrollview.subviews count]; i++ )     {         uiview *v = [scrollview.subviews objectatindex:i];          // not quite right here         float scale = 1. - ( abs(scrollview.center.x - ( v.center.x - scrollview.contentoffset.x ) ) / scrollview.contentsize.width/2 );          v.alpha = scale;          v.transform = cgaffinetransformidentity;         v.transform = cgaffinetransformscale(v.transform, scale, scale);      } } 

if has thoughts, i'd appreciate it, has been long day fighting this.

testing scale calculation can see there's wrong in first part of it. imagine following values: scrollview center x = 10 scrollview contentoffset x = 30 v1 center x = 5 v2 center x = 15

v1 , v2 mirrored (5 pixels left of center , 5 right of center), should return same scale value. if calculation code, returns 35 , 25, means calculation isn't right.

i'm not sure how want scale behave suggestion be:

float scale = 1. - ( (scrollview.contentoffset.x - abs( v.center.x - scrollview.center.x ) ) / scrollview.contentsize.width/2 ); 

edit: try one:

float scale = 1. - (abs( v.center.x - scrollview.center.x ) ) / scrollview.contentsize.width/2 ); 

there many ways of doing calculation. point should make sure operations giving expected results fake values, , yours not. dividend giving wrong results.