Filter Array of NSDictionaries Based on Objects in Separate Array

Question

I have an array of NSDictionaries that I would like to filter. Each dictionary contains the key "tid" which corresponds to a string object. I would like to pull out all dictionaries for which their object for key "tid" is NOT equal to any of the string objects contained in a separate array.

For example, if I have an array called "stringObjects" and an array of dictionaries called "dictionaries", in pseudo code I want to do:

for (NSString *string in stringObjects) {
 //if a dictionary in dictionaries contains a string object for it's key @"tid" which is NOT equal to *string, then put it in an array
}

I've been trying to use NSPredicate to do this, but after several varied attempts, I can't get my desired result. Here is the code I most recently tried (which actually seems to create an array of every object for every dictionary in the array except objects for key @"tid"):

NSSet *savedThreadIds = //set of strings

NSMutableArray *filtered = [NSMutableArray array];

for (NSString *threadId in savedThreadIds) {
      [filtered addObjectsFromArray:[arrayOfDictionaries filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@"(%K != %@)", @"tid", threadId]]];     
}

Any help is appreciated.

Lord Zsolt · Accepted Answer · 2014-05-15 15:43:43Z

0

If I understand your answer correctly, you're looking for NSCompoundPredicate:

NSMutableArray *predicates = [[NSMutableArray alloc] init];
for (NSString *string in stringObjects) {
    //Create an array of predicates
    NSPredicate *pred = [NSPredicate predicateWithFormat:@"NOT (tid CONTAINS[cd] %@)",string];
    [predicates addObject:pred];
}
//Create a compound predicate from predicate array, with format P1 AND P2 AND P3 etc.
NSPredicate *compoundPredicate = [NSCompoundPredicate andPredicateWithSubpredicates:predicates];
//Filter an your array using compoundPredicate.

answered May 15, 2014 at 15:43

Lord Zsolt

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