NSMutableDictionary remove object at key path?

Question

I've got a layered NSMutableDictionary object and i'd like to be able to remove dictionaries deeper down in the hierarchy. Is there a quick and easy way to do this, for example, a removeObjectAtKeyPath-like method? Can't seem to find one.

Thanks!

Answer 1

Nothing built in, but your basic category method will do just fine:

@implementation NSMutableDictionary (WSSNestedMutableDictionaries)

- (void)WSSRemoveObjectForKeyPath: (NSString *)keyPath
{
    // Separate the key path
    NSArray * keyPathElements = [keyPath componentsSeparatedByString:@"."];
    // Drop the last element and rejoin the path
    NSUInteger numElements = [keyPathElements count];
    NSString * keyPathHead = [[keyPathElements subarrayWithRange:(NSRange){0, numElements - 1}] componentsJoinedByString:@"."];
    // Get the mutable dictionary represented by the path minus that last element
    NSMutableDictionary * tailContainer = [self valueForKeyPath:keyPathHead];
    // Remove the object represented by the last element
    [tailContainer removeObjectForKey:[keyPathElements lastObject]];
}

@end

N.B. That this requires that the second-to-last element of the path -- the tailContainer be something that responds to removeObjectForKey:, probably another NSMutableDictionary. If it's not, boom!