Stylesheet like IBInspectable labels

UILabel+Stylesheet.h

//
//  UILabel+Stylesheet.h
//  Stylesheet
//
//  Created by Cyril Chandelier on 21/10/15.
//  Copyright © 2015 CyrilChandelier. All rights reserved.
//

#import <UIKit/UIKit.h>


@interface UILabel (Stylesheet)

+ (void)registerStyleNamed:(nonnull NSString *)name block:(nonnull void(^)(NSString * _Nonnull, NSMutableAttributedString  * _Nonnull , NSMutableParagraphStyle * _Nonnull))block;

@property (nonatomic, strong, nonnull) IBInspectable NSString *styles;

@end

UILabel+Stylesheet.m

//
//  UILabel+Stylesheet.m
//  Stylesheet
//
//  Created by Cyril Chandelier on 21/10/15.
//  Copyright © 2015 CyrilChandelier. All rights reserved.
//

#import "UILabel+Stylesheet.h"

#import <objc/runtime.h>


@implementation UILabel (Stylesheet)

- (void)awakeFromNib
{
    [super awakeFromNib];
    [self refresh];
}

- (void)refresh
{
    NSRange globalRange = NSMakeRange(0, self.text.length);
    NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
    NSMutableAttributedString *attributedText = [[NSMutableAttributedString alloc] initWithString:self.text];
    [attributedText addAttribute:NSParagraphStyleAttributeName value:paragraphStyle range:globalRange];
    for (NSString *style in [self.styles componentsSeparatedByString:@" "])
    {
        void(^block)(NSString *, NSMutableAttributedString *, NSMutableParagraphStyle *) = [[self class] registeredStyles][style];
        block(self.text, attributedText, paragraphStyle);
    }
    self.attributedText = attributedText;
}

#pragma mark - Style registration

+ (void)registerStyleNamed:(nonnull NSString *)name block:(nonnull void(^)(NSString * _Nonnull, NSMutableAttributedString  * _Nonnull , NSMutableParagraphStyle * _Nonnull))block
{
    [[[self class] registeredStyles] setObject:[block copy] forKey:name];
}

#pragma mark - Private getters and setters

static void * stylesKey = &stylesKey;
static void * registeredStylesKey = &registeredStylesKey;

- (NSString *)styles
{
    return objc_getAssociatedObject(self, &stylesKey);
}

- (void)setStyles:(NSString *)styles
{
    objc_setAssociatedObject(self, &stylesKey, styles, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    [self refresh];
}

+ (NSMutableDictionary *)registeredStyles
{
    NSMutableDictionary *registeredStyles = objc_getAssociatedObject(self, &registeredStylesKey);
    if (!registeredStyles)
    {
        registeredStyles = [NSMutableDictionary dictionary];
        objc_setAssociatedObject(self, &registeredStylesKey, registeredStyles, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    }
    
    return registeredStyles;
}

@end

Wherever.m

#import "UILabel+Stylesheet.h"

[UILabel registerStyleNamed:@"title" block:^(NSString *text, NSMutableAttributedString *attributedText, NSMutableParagraphStyle *paragraphStyle) {
            [attributedText addAttribute:NSFontAttributeName value:[UIFont boldSystemFontOfSize:30.0f] range:NSMakeRange(0, [text length])];
}];
[UILabel registerStyleNamed:@"content" block:^(NSString *text, NSMutableAttributedString *attributedText, NSMutableParagraphStyle *paragraphStyle) {
    [attributedText addAttribute:NSFontAttributeName value:[UIFont systemFontOfSize:22.0f] range:NSMakeRange(0, [text length])];
}];
[UILabel registerStyleNamed:@"color" block:^(NSString *text, NSMutableAttributedString *attributedText, NSMutableParagraphStyle *paragraphStyle) {
    [attributedText addAttribute:NSForegroundColorAttributeName value:[UIColor blueColor] range:NSMakeRange(0, [text length])];
}];
[UILabel registerStyleNamed:@"center" block:^(NSString *text, NSMutableAttributedString *attributedText, NSMutableParagraphStyle *paragraphStyle) {
    paragraphStyle.alignment = NSTextAlignmentCenter;
}];
[UILabel registerStyleNamed:@"red" block:^(NSString *text, NSMutableAttributedString *attributedText, NSMutableParagraphStyle *paragraphStyle) {
    [attributedText addAttribute:NSForegroundColorAttributeName value:[UIColor redColor] range:NSMakeRange(0, [text length])];
}];