Obj-C - NSPredicate - Can I implement an 'or IF' statement? - ios

Question

I'm trying to write a filter with NSPredicate that states:
IF field_Uid contains 47 and field_Target contains 202...display these items
This portion works great. However, I also want to show items in which the reverse is true, eg.:
OR IF fieldUid contains 202 and fieldTarget contains 47...display these
items also
Right now, I have the following code:
NSString *targetedUser = #"47";
NSString *myID = #"202";
NSPredicate *p1 = [NSPredicate predicateWithFormat:#"fieldUid contains[cd] %#", targetedUser];
NSPredicate *p2 = [NSPredicate predicateWithFormat:#"fieldTarget contains[cd] %#", myID];
//E.G. See p3 & p4 being the reverse?
// NSPredicate *p3 = [NSPredicate predicateWithFormat:#"fieldUid contains[cd] %#", myID];
// NSPredicate *p4 = [NSPredicate predicateWithFormat:#"fieldTarget contains[cd] %#", targetedUser];
NSCompoundPredicate *p = [NSCompoundPredicate andPredicateWithSubpredicates:#[p1, p2/*, p3, p4*/]];
NSArray *filtered = [self.messages filteredArrayUsingPredicate:p];
How would I write in the latter? I'm not sure how to do it without making the statement requiring all 4 lines to be true? (See commented out code - I've left it in so you can see what I mean...)

Answer 1

Just combine two compound "and" predicates using a compound "or" predicate.
You have the first compound "and" predicate in your question. Create the 2nd compound "and" predicate as needed.
Now use [NSCompoundPredicate orPredicateWithSubpredicates:] passing in the two "and" compound predicates.

Answer 2

you can also use
NSString *targetedUser = #"47";
NSString *myID = #"202";
//this will easily fix your issue, simply update your query like this
NSPredicate *p = [NSPredicate predicateWithFormat:#"(fieldUid contains[cd] %# AND fieldTarget contains[cd] %#) OR (fieldUid contains[cd] %# AND fieldTarget contains[cd] %#)", targetedUser, myID, myID, targetedUser];
NSArray *filtered = [self.messages filteredArrayUsingPredicate:p];