Introduce the -apply: method for all collections. Fixes issue #14.

-apply: is remarkably similar to -each:, with the primary difference being that enumeration is concurrent under -apply: instead of sequential. This means a noticeable speed increase, but also increased danger for the programmer. Use wisely.
Signed-off-by: Zachary Waldowski <zwaldowski@gmail.com>

BlocksKit/NSArray+BlocksKit.h

@@ -30,6 +30,20 @@
  */
 - (void)each:(BKSenderBlock)block;
 
+/** Enumerates through an array concurrently and executes
+ the given block once for each object.
+ 
+ Enumeration will occur on appropriate background queues. This
+ will have a noticeable speed increase, especially on dual-core
+ devices, but you *must* be aware of the thread safety of the
+ objects you message from within the block. Be aware that the
+ order of objects is not necessarily the order each block will
+ be called in.
+ 
+ @param block A single-argument, void-returning code block.
+ */
+- (void)apply:(BKSenderBlock)block;
+
 /** Loops through an array to find the object matching the block.
  
  match: is functionally identical to select:, but will stop and return

BlocksKit/NSArray+BlocksKit.m

@@ -8,11 +8,17 @@
 @implementation NSArray (BlocksKit)
 
 - (void)each:(BKSenderBlock)block {
-    [self enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
+     [self enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
         block(obj);
     }];
 }
 
+- (void)apply:(BKSenderBlock)block {
+	[self enumerateObjectsWithOptions:NSEnumerationConcurrent usingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
+		block(obj);
+	}];
+}
+
 - (id)match:(BKValidationBlock)block {
     NSUInteger index = [self indexOfObjectPassingTest:^BOOL(id obj, NSUInteger idx, BOOL *stop) {
         return block(obj);

BlocksKit/NSDictionary+BlocksKit.h

@@ -27,6 +27,19 @@
  */
 - (void)each:(BKKeyValueBlock)block;
 
+/** Enumerates through the dictionary concurrently and executes
+ the given block once for each pair.
+ 
+ Enumeration will occur on appropriate background queues;
+ the system will spawn threads as need for execution. This
+ will have a noticeable speed increase, especially on dual-core
+ devices, but you *must* be aware of the thread safety of the
+ objects you message from within the block.
+ 
+ @param block A block that performs an action using a key/value pair.
+ */
+- (void)apply:(BKKeyValueBlock)block;
+
 /** Loops through a dictionary to find the key/value pairs matching the block.
  
  @param block A BOOL-returning code block for a key/value pair.

BlocksKit/NSDictionary+BlocksKit.m

@@ -13,6 +13,12 @@ - (void)each:(BKKeyValueBlock)block {
     }];
 }
 
+- (void)apply:(BKKeyValueBlock)block {
+	[self enumerateKeysAndObjectsWithOptions:NSEnumerationConcurrent usingBlock:^(id key, id obj, BOOL *stop) {
+		block(key, obj);
+	}];
+}
+
 - (NSDictionary *)select:(BKKeyValueValidationBlock)block {
     NSMutableDictionary *list = [NSMutableDictionary dictionaryWithCapacity:self.count];
 

BlocksKit/NSIndexSet+BlocksKit.h

@@ -30,6 +30,17 @@
  */
 - (void)each:(BKIndexBlock)block;
 
+/** Enumerates each index in an index set concurrently and executes the
+ given block once per index.
+ 
+ Enumeration will occur on appropriate background queues. 
+ Be aware that the block will not necessarily be executed
+ in order for each index.
+ 
+ @param block A single-argument, void-returning code block.
+ */
+- (void)apply:(BKIndexBlock)block;
+
 /** Loops through an array and returns the index matching the block.
  
  @param block A single-argument, `BOOL`-returning code block.

BlocksKit/NSIndexSet+BlocksKit.m

@@ -13,6 +13,12 @@ - (void)each:(BKIndexBlock)block {
     }];
 }
 
+- (void)apply:(BKIndexBlock)block {
+	[self enumerateIndexesWithOptions:NSEnumerationConcurrent usingBlock:^(NSUInteger idx, BOOL *stop) {
+		block(idx);
+	}];
+}
+
 - (NSUInteger)match:(BKIndexValidationBlock)block {
     return [self indexPassingTest:^BOOL(NSUInteger idx, BOOL *stop) {
         return block(idx);

BlocksKit/NSSet+BlocksKit.h

@@ -30,6 +30,18 @@
  */
 - (void)each:(BKSenderBlock)block;
 
+/** Enumerates through a set concurrently and executes
+ the given block once for each object.
+ 
+ Enumeration will occur on appropriate background queues. This
+ will have a noticeable speed increase, especially on dual-core
+ devices, but you *must* be aware of the thread safety of the
+ objects you message from within the block.
+ 
+ @param block A single-argument, void-returning code block.
+ */
+- (void)apply:(BKSenderBlock)block;
+
 /** Loops through a set to find the object matching the block.
 
  match: is functionally identical to select:, but will stop and return

BlocksKit/NSSet+BlocksKit.m

@@ -13,6 +13,12 @@ - (void)each:(BKSenderBlock)block {
     }];
 }
 
+- (void)apply:(BKSenderBlock)block {
+	[self enumerateObjectsWithOptions:NSEnumerationConcurrent usingBlock:^(id obj, BOOL *stop) {
+		block(obj);
+	}];
+}
+
 - (id)match:(BKValidationBlock)block {
     return [[self objectsPassingTest:^BOOL(id obj, BOOL *stop) {
         if (block(obj)) {