Case Insensitive Search in NSMutableDictionary - ios

Question

HI, I have a NSMutableDicitionary contains both lowercase and uppercase keys. So currently i don't know how to find the key in the dictionary irrespective key using objective c.

Answer 1

Categories to the rescue.
Ok, so it's an old post...
#interface NSDictionary (caseINsensitive)
-(id) objectForCaseInsensitiveKey:(id)aKey;
#end
#interface NSMutableDictionary (caseINsensitive)
-(void) setObject:(id) obj forCaseInsensitiveKey:(id)aKey ;
#end
#implementation NSDictionary (caseINsensitive)
-(id) objectForCaseInsensitiveKey:(id)aKey {
for (NSString *key in self.allKeys) {
if ([key compare:aKey options:NSCaseInsensitiveSearch] == NSOrderedSame) {
return [self objectForKey:key];
}
}
return nil;
}
#end
#implementation NSMutableDictionary (caseINsensitive)
-(void) setObject:(id) obj forCaseInsensitiveKey:(id)aKey {
for (NSString *key in self.allKeys) {
if ([key compare:aKey options:NSCaseInsensitiveSearch] == NSOrderedSame) {
[self setObject:obj forKey:key];
return;
}
}
[self setObject:obj forKey:aKey];
}
#end
enjoy.

Answer 2

Do you have control over the creation of the keys? If you do, I'd just force the keys to either lower or upper case when you're creating them. This way when you need to look up something, you don't have to worry about mixed case keys.

Answer 3

You can do this to get the object as an alternative to subclassing.
__block id object;
[dictionary enumerateKeysAndObjectsWithOptions:NSEnumerationConcurrent
UsingBlock:^(id key, id obj, BOOL *stop){
if ( [key isKindOfClass:[NSString class]] ) {
if ( [(NSString*)key caseInsensitiveCompare:aString] == NSOrderedSame ) {
object = obj; // retain if wish to.
*stop = YES;
}
}
}];
You can use a #define shorthand if you find yourself doing this a lot in your code.

Answer 4

Don't think there's any easy way. Your best option might be to create a subclass of NSMutableDictionary, and override the objectForKey and setObject:ForKey methoods. Then in your overridden methods ensure that all keys are converted to lowercase (or uppercase), before passing them up to the superclass methdods.
Something along the lines of the following should work:
#Interface CaseInsensitveMutableDictionary : MutableDictionary {}
#end
#implementation CaseInsensitveMutableDictionary
- (void) setObject: (id) anObject forKey: (id) aKey {
[super setObject:anObject forKey:[skey lowercaseString]];
}
- (id) objectForKey: (id) aKey {
return [super objectForKey: [aKey lowercaseString]];
}
#end