Function to create an NSArray with the results of calling a block on every object from an existing NSArray.

PRHArrayByMap.h

extern NSArray *PRHArrayByMap(NSArray *inArray, id (^block)(id));

PRHArrayByMap.m

NSArray *PRHArrayByMap(NSArray *inArray, id (^block)(id)) {
	if (inArray == nil)
		return nil;

	NSCParameterAssert(block != nil);

	NSMutableArray *outArray = [NSMutableArray arrayWithCapacity:inArray.count];
	for (id obj in inArray) {
		id result = block(obj);
		NSCAssert(result != nil, @"%s: block(%@) returned nil—array follows\n%@", __func__, obj, inArray);
		[outArray addObject:result];
	}

	return outArray;
}