Changing selected TabBarItem font iOS

Good news and bad news.

Bad news, It's a little harder than just using the appearance proxy.

Good news It's not that much harder!

Header

#import <UIKit/UIKit.h>

@interface MYTabbyViewController : UITabBarController

@end

Implementation

#import "MYTabbyViewController.h"

@implementation MYTabbyViewController

-(void)setSelectedViewController:(UIViewController *)selectedViewController
{
    [super setSelectedViewController:selectedViewController];

    for (UIViewController *viewController in self.viewControllers) {
        if (viewController == selectedViewController) {
            [viewController.tabBarItem setTitleTextAttributes:@{
                                                    NSFontAttributeName: [UIFont fontWithName:@"HelveticaNeue-Medium" size:16],
                                                    NSForegroundColorAttributeName: [UIColor blueColor]
                                                    }
                                         forState:UIControlStateNormal];
        } else {
            [viewController.tabBarItem setTitleTextAttributes:@{
                                                    NSFontAttributeName: [UIFont fontWithName:@"HelveticaNeue-Light" size:16],
                                                    NSForegroundColorAttributeName: [UIColor grayColor]
                                                    }
                                         forState:UIControlStateNormal];
        }
    }
}

The last part you will need is to use this subclass instead of the out-of-the-box UITabBarController. If you are using Storyboards, simply select the TabBarController, go to the Identity Inspector (third subtab in the right panel) and change UITabBarController to MYTabBarController or what have you.

But yeah! Bottom line, just update the ViewController tabBarItem!

@Acey´s answer in Swift 3:

    override var selectedViewController: UIViewController? {
    didSet {

        guard let viewControllers = viewControllers else {
            return
        }

        for viewController in viewControllers {

            if viewController == selectedViewController {

                let selected: [String: AnyObject] =
                    [NSFontAttributeName: UIFont.systemFont(ofSize: 11, weight: UIFontWeightHeavy),
                     NSForegroundColorAttributeName: UIColor.red]

                viewController.tabBarItem.setTitleTextAttributes(selected, for: .normal)

            } else {

                let normal: [String: AnyObject] =
                    [NSFontAttributeName: UIFont.systemFont(ofSize: 11),
                     NSForegroundColorAttributeName: UIColor.blue]

                viewController.tabBarItem.setTitleTextAttributes(normal, for: .normal)

            }
        }
    }
}