Remove duplicates in NSdictionary

问题

Is there a way to remove duplicate (key-value) pairs from NSDictionary ?

EDIT: My description was misleading, I have duplicate pairs e.g.
key1-value1
key1-value1
key2-value2
key1-value1
etc..

回答1:

reversing key-value is not good idea because not all values can be keys. You can do it with:

// dict is original dictionary, newDict new dictionary withot duplicates.

NSMutableDictionary * newDict = [NSMutableDictionary dictionaryWithCapacity:[dict count]];
for(id item in [dict allValues]){
    NSArray * keys = [dict allKeysForObject:item];
    [newDict setObject:item forKey:[keys objectAtIndex:0]];
}

yuo can also use lastObject instead of objectAtIndex:0 to leave other key for dup objects

回答2:

One way is to put the key/value pairs into a dictionary by value/key and then converting that back to key/value.

回答3:

I can't think of a built-in method.

If you iterate over the values, allKeysForObject: will give you an array of keys for each value and if you have more more than one key, that value has duplicates.

来源：https://stackoverflow.com/questions/2462481/remove-duplicates-in-nsdictionary