NSDateFormatter+IkuramediaLazyFormatter.h

//
//  NSDateFormatter+IkuramediaLazyFormatter.h
//
//  Created by Price Stephen on 11/08/2013.
//  For Ikura Group Limited.
//

#import <Foundation/Foundation.h>

typedef void(^IMLazyDateFormatterBlock)(NSDateFormatter *);
typedef NSString* IMLazyDateFormatterToken;

@interface NSDateFormatter (IkuramediaLazyFormatter)

/***
 Snippet: IMKeyedLazyFormatter

 NSDateFormatter *dateFormatter = [NSDateFormatter lazyDateFormatterWithKey:<#Key#>
 configurationBlock:^(NSDateFormatter *dateFormatter)
 {
    <#code#>
 }];
 ***/

+ (NSDateFormatter *)lazyDateFormatterWithKey:(NSString *)key
                          configurationBlock:(IMLazyDateFormatterBlock)configurationBlock;

/***
 Snippet: IMLazyFormatter
 
 static IMLazyDateFormatterToken dateToken;
 NSDateFormatter *dateFormatter = [NSDateFormatter lazyDateFormatterWithToken:&dateToken
                                    configurationBlock:^(NSDateFormatter *dateFormatter)
                                    {
                                        <#code#>
                                    }];
 ***/

+ (NSDateFormatter *)lazyDateFormatterWithToken:(IMLazyDateFormatterToken __strong*)token
                             configurationBlock:(IMLazyDateFormatterBlock)configurationBlock;

@end

NSDateFormatter+IkuramediaLazyFormatter.m

//
//  NSDateFormatter+IkuramediaLazyFormatter.m
//
//  Created by Price Stephen on 11/08/2013.
//  For Ikura Group Limited.
//

#import "NSDateFormatter+IkuramediaLazyFormatter.h"

@implementation NSDateFormatter (IkuramediaLazyFormatter)

static NSMutableDictionary *imLazyDictionary = nil;

+ (NSDateFormatter *)lazyDateFormatterWithToken:(NSString * __strong*)tokenString
                             configurationBlock:(IMLazyDateFormatterBlock)configurationBlock;
{
    if (*tokenString == nil)
    {
        *tokenString = [[NSUUID UUID] UUIDString];
    }
    
    return [self lazyDateFormatterWithKey:*tokenString
                      configurationBlock:configurationBlock];
}

+ (NSDateFormatter *)lazyDateFormatterWithKey:(NSString *)identifier
                          configurationBlock:(IMLazyDateFormatterBlock)configurationBlock;
{
    if (imLazyDictionary == nil)
    {
        static dispatch_once_t onceToken;
        dispatch_once(&onceToken, ^{
            imLazyDictionary = NSMutableDictionary.dictionary;
        });
    }

    @synchronized(self)
    {
        if (imLazyDictionary[identifier]) return imLazyDictionary[identifier];

        NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
        if (configurationBlock) configurationBlock(dateFormatter);
        imLazyDictionary[identifier] = dateFormatter;

        return dateFormatter;
    }
}

@end