Been looking around and trying to change just the border color (with a different text color) with no luck. Can change the tint, but changes both the text and border.
What worked for me: is as other answers suggest, change the tintColor of the segmentedControl to clearColor. And manually tint the images to your app tint color.
Remember to use the imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal
on the tinted image
-(UIImage *)tintedImage:(UIImage *)image withColor:(UIColor *)tintColor
{
UIGraphicsBeginImageContextWithOptions(image.size, NO, 0.0);
CGContextRef context = UIGraphicsGetCurrentContext();
CGRect rect = (CGRect){ CGPointZero, image.size };
CGContextSetBlendMode(context, kCGBlendModeNormal);
[image drawInRect:rect];
CGContextSetBlendMode(context, kCGBlendModeSourceIn);
[tintColor setFill];
CGContextFillRect(context, rect);
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return [newImage imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];
}