Changing the segment divider image:
[segmentControl setDividerImage:dividerimg
forLeftSegmentState:UIControlStateNormal
rightSegmentState:UIControlStateNormal
barMetrics:UIBarMetricsDefault];
Or using core graphics
UIGraphicsBeginImageContextWithOptions(CGSizeMake(1, self.segControlOut.frame.size.height), NO, 0.0);
UIImage *blank = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
[self.segControlOut setDividerImage:blank
forLeftSegmentState:UIControlStateNormal
rightSegmentState:UIControlStateNormal
barMetrics:UIBarMetricsDefault];