Using NSPredicate to search through array of objects - objective-c

Question

I have an array of instances of a class called Contact, which has, among others, the following properties:
NSArray *mailAddressList // Array of NSString
NSArray *websiteList // Array of NSString
NSArray *tags // Array of instances of Tag class
The class tag has the following properties:
NSString *name;
UIColor *color;
I want to use NSPredicate to search a string in any property of each Contact. This is the code I have:
if([scope isEqualToString:SCOPE_MAIL] || [scope isEqualToString:SCOPE_WEBSITE])
{
// Search through an array
predicate = [NSPredicate predicateWithFormat:#"ANY SELF.%# contains[c] %#", scope, textSearch];
}
else if([scope isEqualToString:SCOPE_TAG])
{
// Search another object's property
predicate = [NSPredicate predicateWithFormat:#"SELF.%#.name contains[c] %#", scope, textSearch];
}
else
{
// The rest of the properties are instances of NSString
predicate = [NSPredicate predicateWithFormat:#"SELF.%# contains[c] %#", scope, textSearch];
}
Everything works fine except for SCOPE_TAG, it doesn't return any values. I don't think I'm using the predicate correctly.
NOTE: I'm new with NSPredicate so I would like to hear some insights if what I'm doing is not ok

Answer 1

First of all, if you substitute a keypath you should use %K as arg.
Further, I think you are missing the ANY argument in your second query. I think you want a result if any of the tag names contains your textSearch.
To get a better understanding of how predicates work, have a look at the Apple Documentation
I did a quick test and it is still working fine:
NSMutableArray *arrayContacts = [NSMutableArray array];
{
AMContact *contact = [[AMContact alloc] init];
NSMutableArray *arrayTags = [NSMutableArray array];
{
AMTags *tag = [[AMTags alloc] init];
tag.name = #"Test";
[arrayTags addObject:tag];
}
{
AMTags *tag = [[AMTags alloc] init];
tag.name = #"Te2st2";
[arrayTags addObject:tag];
}
{
AMTags *tag = [[AMTags alloc] init];
tag.name = #"No";
[arrayTags addObject:tag];
}
contact.tags = [arrayTags copy];
[arrayContacts addObject:contact];
}
{
AMContact *contact = [[AMContact alloc] init];
NSMutableArray *arrayTags = [NSMutableArray array];
{
AMTags *tag = [[AMTags alloc] init];
tag.name = #"Test";
[arrayTags addObject:tag];
}
contact.tags = [arrayTags copy];
[arrayContacts addObject:contact];
}
NSPredicate *pred = [NSPredicate predicateWithFormat:#"ANY SELF.%K.name contains[c] %#", #"tags", #"Test"];
NSArray *result = [arrayContacts filteredArrayUsingPredicate:pred];
NSLog(#"%#", result);