How to customize UILabel’s font using UIAppearance.

RGMAppDelegate.m

//
//  RGMAppDelegate.m
//  UILabel+Appearance
//
//  Created by Ryder Mackay on 2013-06-04.
//  Copyright (c) 2013 Ryder Mackay. All rights reserved.
//

#import "RGMAppDelegate.h"
#import "UILabel+Appearance.h"

@implementation RGMAppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    UILabel *label = [UILabel appearance];
    label.rgm_font = [UIFont fontWithName:@"Avenir" size:17];
    
    return YES;
}

@end

UILabel+Appearance.h

//
//  UILabel+Appearance.h
//  UILabel+Appearance
//
//  Created by Ryder Mackay on 2013-06-04.
//  Copyright (c) 2013 Ryder Mackay. All rights reserved.
//

#import <UIKit/UIKit.h>

@interface UILabel (Appearance)

@property (nonatomic, strong) UIFont *rgm_font UI_APPEARANCE_SELECTOR;

@end

UILabel+Appearance.m

//
//  UILabel+Appearance.m
//  UILabel+Appearance
//
//  Created by Ryder Mackay on 2013-06-04.
//  Copyright (c) 2013 Ryder Mackay. All rights reserved.
//

#import "UILabel+Appearance.h"

@implementation UILabel (Appearance)

- (UIFont *)rgm_font
{
    return self.font;
}

- (void)setRgm_font:(UIFont *)rgm_font
{
    self.font = rgm_font;
}

@end