UISegmentedControl+iOS7Flat.h

@interface UISegmentedControl (iOS7Flat)
- (void)flattenUIWithFont:(UIFont *)font tintColor:(UIColor *)tintColor highlightedTextColor:(UIColor *)highlightedTextColor;
@end

UISegmentedControl+iOS7Flat.m

#import "UISegmentedControl+iOS7Flat.h"

@interface UIImage (Additions)
+ (UIImage *)imageWithColor:(UIColor *)color;
+ (UIImage *)imageWithColor:(UIColor *)color size:(CGSize)size andRoundSize:(CGFloat)roundSize;
@end

@implementation UIImage (Additions)

+ (UIImage *)imageWithColor:(UIColor *)color {
    CGRect rect = CGRectMake(0.0f, 0.0f, 1.0f, 1.0f);
    UIGraphicsBeginImageContext(rect.size);
    CGContextRef context = UIGraphicsGetCurrentContext();

    CGContextSetFillColorWithColor(context, [color CGColor]);
    CGContextFillRect(context, rect);

    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return image;
}

+ (UIImage *)imageWithColor:(UIColor *)color size:(CGSize)size andRoundSize:(CGFloat)roundSize {

    CGRect rect = CGRectMake(0.0f, 0.0f, size.width, size.height);
    UIGraphicsBeginImageContextWithOptions(rect.size, NO, [UIScreen mainScreen].scale);
    CGContextRef context = UIGraphicsGetCurrentContext();

    if (roundSize > 0) {
        UIBezierPath* roundedRectanglePath = [UIBezierPath bezierPathWithRoundedRect:rect cornerRadius: roundSize];
        [color setFill];
        [roundedRectanglePath fill];
    } else {
        CGContextSetFillColorWithColor(context, [color CGColor]);
        CGContextFillRect(context, rect);

    }

    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    return image;
}

@end



@implementation UISegmentedControl (iOS7Flat)

- (void)flattenUIWithFont:(UIFont *)font tintColor:(UIColor *)tintColor highlightedTextColor:(UIColor *)highlightedTextColor
{
    CGRect f = self.frame;
    f.size.height -= font.pointSize; // height minus font size, to prevent big segmented control on iOS 6
    self.frame = f;

    self.layer.cornerRadius = 5.0f;
    self.layer.borderWidth = 1.0f;
    self.layer.borderColor = tintColor.CGColor;

    UIImage *normalBackgroundImage = [UIImage imageWithColor:tintColor size:CGSizeMake(10.0f, 40.0f) andRoundSize:5.0f];
    UIImage *selectedBackgroundImage = [UIImage imageWithColor:[UIColor clearColor] size:CGSizeMake(10.0f, 40.0f) andRoundSize:5.0f];

    NSDictionary *attributes = @{UITextAttributeFont: font,
                                 UITextAttributeTextColor: tintColor,
                                 UITextAttributeTextShadowOffset: [NSValue valueWithCGSize:CGSizeZero],
                                 UITextAttributeTextShadowColor: [UIColor clearColor]};
    [self setTitleTextAttributes:attributes forState:UIControlStateNormal];
    [self setTitleTextAttributes:attributes forState:UIControlStateDisabled];
    [self setTitleTextAttributes:attributes forState:UIControlStateReserved];
    [self setTitleTextAttributes:attributes forState:UIControlStateApplication];

    NSDictionary *highlightedAttributes = @{UITextAttributeFont: font,
                                            UITextAttributeTextColor: highlightedTextColor,
                                            UITextAttributeTextShadowOffset: [NSValue valueWithCGSize:CGSizeZero],
                                            UITextAttributeTextShadowColor: [UIColor clearColor]};
    [self setTitleTextAttributes:highlightedAttributes forState:UIControlStateHighlighted];
    [self setTitleTextAttributes:highlightedAttributes forState:UIControlStateSelected];

    [self setBackgroundImage:selectedBackgroundImage
                    forState:UIControlStateNormal
                  barMetrics:UIBarMetricsDefault];

    [self setBackgroundImage:normalBackgroundImage
                    forState:UIControlStateSelected
                  barMetrics:UIBarMetricsDefault];

    [self setDividerImage:[UIImage imageWithColor:tintColor]
      forLeftSegmentState:UIControlStateNormal
        rightSegmentState:UIControlStateNormal
               barMetrics:UIBarMetricsDefault];
}

@end