Apple WebObjects 3.5 - Manual (Page 203)

Commonly Used Dictionary Methods
203
Querying Dictionaries
– allKeys
Returns an array containing the dictionary’s keys or an empty array
if the dictionary has no entries. This method is useful for accessing
all the entries in a dictionary. For example, the following code
excerpt creates the NSArray
keys and uses it to access the value of
each entry in the dictionary:
id index;
id keys = [dictionary allKeys];
for (index = 0; index < [keys count]; index++) {
value = [dictionary objectForKey:[keys
objectAtIndex:index]];
// Use the value
}
– allKeysForObject:
Returns an array containing all the keys corresponding to values
equivalent to a specified object. Equivalency is determined using
the
isEqual: method. If the specified object isn’t equivalent to any of
the values in the receiver, this method returns nil .
– allValues:
Returns an array containing the dictionary’s values, or an empty
array if the dictionary has no entries.
Note that the array returned from allValues may have a different
count than the array returned from allKeys . An object can be in a
dictionary more than once if it corresponds to multiple keys.
– keysSortedByValueUsingSelector:
Returns an NSArray containing the dictionary’s keys such that
their corresponding values are sorted in ascending order, as
determined by a specified method. For example, the following
code excerpt creates the NSArray
keys containing the string
“Pasta” at index 0, “Seafood” at index 1, and “Steak” at index 2:
id choices = @{"Steak" = 3; "Seafood" = 2; "Pasta" = 1};
id keys = [choices sortedByValueUsingSelector:@"compare:"];
– count
Returns the number of entries currently in the dictionary.