gistfile1.txt

@implementation NSDictionary (MapDictKeysContainingPeriods)

- (NSDictionary *)dictionaryWithPeriodsInKeysMappedTo:(NSString *)replacement
{
    NSMutableDictionary *updatedDictionary = [self mutableCopy];
    NSAssert1(updatedDictionary != self, @"mutableCopy returned same object pointer: %@", updatedDictionary); // i don't think this ever happens
    BOOL changed = NO;
    for (NSString *key in updatedDictionary.allKeys)
    {
        id value = [updatedDictionary objectForKey:key];
        id newValue = value;
        
        if ([value isKindOfClass:[NSArray class]])
        {
            newValue = [value arrayWithPeriodsInDictionaryKeysMappedTo:replacement];
        }
        else if ([value isKindOfClass:[NSDictionary class]])
        {
            newValue = [value dictionaryWithPeriodsInKeysMappedTo:replacement];
        }
        
        NSMutableString *updatedKey = [key mutableCopy];
        if ([updatedKey replaceOccurrencesOfString:@"." withString:replacement options:0 range:NSMakeRange(0, key.length)] > 0)
        {
            [updatedDictionary removeObjectForKey:key];
            [updatedDictionary setObject:newValue forKey:updatedKey];
            changed = YES;
        }
        else if (newValue != value)
        {
            [updatedDictionary setObject:newValue forKey:key];
            changed = YES;
        }
    }
    return changed ? updatedDictionary : self;
}

@end

@implementation NSArray (MapDictKeysContainingPeriods)

- (NSArray *)arrayWithPeriodsInDictionaryKeysMappedTo:(NSString *)replacement
{
    NSMutableArray *updatedArray = [self mutableCopy];
    NSAssert1(updatedArray != self, @"mutableCopy returned same object pointer: %@", updatedArray); // i don't think this ever happens
    BOOL changed = NO;
    NSUInteger index = 0;
    for (id element in updatedArray)
    {
        id newElement = element;
        
        if ([element isKindOfClass:[NSArray class]])
        {
            newElement = [element arrayWithPeriodsInDictionaryKeysMappedTo:replacement];
        }
        else if ([element isKindOfClass:[NSDictionary class]])
        {
            newElement = [element dictionaryWithPeriodsInKeysMappedTo:replacement];
        }
        
        if (newElement != element)
        {
            [updatedArray replaceObjectAtIndex:index withObject:newElement];
            changed = YES;
        }
        ++index;
    }
    return changed ? updatedArray : self;
}

@end