Objective-c: Dependecy Injection Class

gistfile1

//
//  SRSDependencyBuilder.m
//
//  Created by Tim Westbaker on 2/5/14.
//  Copyright (c) 2014 Double Blue Sports. All rights reserved.
//
// Objective C version of 
// Original PHP code: http://net.tutsplus.com/tutorials/php/dependency-injection-huh/

#import <Foundation/Foundation.h>

#import "SRSDependencyBuilder.h"

@interface SRSDependencyBuilder : NSObject
@end

@implementation SRSDependencyBuilder

/** Stores creation rules */
static NSMutableDictionary *registry;

/**
 * Add a new resolver to the registry array.
 * @param  string $name The id
 * @param  object $resolve Closure that creates instance
 * @return void
 */
+(void) assign:(NSString *)key createBlock:( id (^)())block
{
    registry[key] = block;
}

/**
 * Create the instance
 * @param  string $name The id
 * @return mixed
 */
+(id) resolve:(NSString *)key
{
    if ( registry[key] )
    {
        id (^ createBlock)();
        createBlock = registry[key];
        return createBlock();
    }
    
    [NSException raise:@"Block doesn't exist" format:@"Can't resolve for key %@", key];
    return nil;
}

@end