Finding distinct array elements based on dictionary key - ios

Question

I have two arrays of key-value pairs. Both these arrays contain different key-value pairs. I want to find elements in the first array that are not part of the second array based on a particular key.
Example:
1st Array - [{id=1, name="foo"},
{id=2, name="bar"}]
2nd Array - [{id=2, name="abc"},
{id=1, name="xyz"}]
Is there a way I can implement the same?
Right now I enumerate through the two arrays like so:
for (NSDictionary *eachPlayer in 1stArray) {
for (NSDictionary *eachPrediction in 2ndArray) {
if (eachPrediction[kId] != eachPlayer[kId]) {
[self.predictPlayerArray addObject:eachPlayer];
}
}
}
But this fails in the above case and adds both the values to the predictionPlayerArray - in the first iteration it adds 1 and in the forth iteration it adds 2. How do I prevent that from happening?
Thanks.
EDIT
I seem to have solved it this way. Not the best solution but it seems to be working:
for (NSDictionary *eachPlayer in arrayOne) {
for (NSDictionary *eachPrediction in arrayTwo) {
if (eachPrediction[kId] == eachPlayer[kId]) {
if ([self.predictPlayerArray containsObject:eachPlayer]) {
[self.predictPlayerArray removeObject:eachPlayer];
}
break;
}
else {
[self.predictPlayerArray addObject:eachPlayer];
}
self.predictPlayerArray = [self.predictPlayerArray valueForKeyPath:#"#distinctUnionOfObjects.self"];
}
}

Answer 1

Something like this should do:
NSArray *array1 = #[#{#"1":#"foo"},#{#"2":#"bar"},#{#"3":#"abc"}];
NSArray *array2 = #[#{#"2":#"abc"},#{#"1":#"abc"},#{#"4":#"foo"}];
NSMutableSet *result = [NSMutableSet new];
for (NSDictionary *dict1 in array1){
[dict1 enumerateKeysAndObjectsUsingBlock:^(id key1, id obj1, BOOL *stop1) {
for (NSDictionary *dict2 in array2) {
[dict2 enumerateKeysAndObjectsUsingBlock:^(id key2, id obj2, BOOL *stop2) {
if ([obj2 isEqual:obj1]){
[result addObject:#{key1:obj1}];
*stop2 = YES;
}
}];
}
}];
}
NSLog(#"result %#", result);
As you has nested dictionaries you should iterate also in them and finally store the result in a set that would prevent to have duplicate entries (if you use a NSMutableArray you will have twice {3:abc})
The log output is:
2015-02-03 13:53:07.897 test[19425:407184] result {(
{
1 = foo;
},
{
3 = abc;
}
)}