A few Objective-C blocks additions for NSArray

BlocksAdditions.h

@interface NSArray(BlocksAdditions)

- (NSArray*)mapUsingBlock:(id (^)(id obj))block;
- (NSSet*)mapToSetUsingBlock:(id (^)(id obj))block;
- (id)firstUsingBlock:(BOOL(^)(id obj))block;

@end

BlocksAdditions.m

#import "BlocksAdditions.h"

#pragma mark -
@implementation NSArray(BlocksAdditions)

- (NSArray*)mapUsingBlock:(id (^)(id obj))block {
	NSMutableArray *new = [NSMutableArray array];
	for(id obj in self)
	{
		id newObj = block(obj);
		[new addObject: newObj ? newObj : [NSNull null]];
	}
	return new;
}

- (NSSet*)mapToSetUsingBlock:(id (^)(id obj))block {
	NSMutableSet *new = [NSMutableSet set];
	for (id obj in self) {
		id newObj = block(obj);
		[new addObject:newObj ? newObj : [NSNull null]];
	}
	return new;
}

- (id)firstUsingBlock:(BOOL(^)(id obj))block {
	for(id obj in self) {
		if (block(obj))
			return obj;
	}
	return nil;
}

@end