CODEWITHSUNDEEP
objective-cioscocoa-touch
vargonian
vargonian

Reputation: 3234

Use an NSPredicate to detect NOT CONTAINS

I give up. I have tried every combination I can imagine to check if a string contains another string. Here's an example of intuitive syntax describing what I want to do:

    NSPredicate* pPredicate = [NSPredicate predicateWithFormat:@"NOT (%K CONTAINS[c] %@)",
NSMetadataItemFSNameKey, 
[NSString stringWithFormat:@"Some String"]];

Regardless of how I shift the NOT around, use the ! operator instead, shift the parentheses or remove them altogether, I always get an exception parsing this expression.

What is wrong with this expression?

EDIT: The exception happens when I call

[pMetadataQuery setPredicate:pPredicate];

and the exception is: * Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Unknown type of NSComparisonPredicate given to NSMetadataQuery (kMDItemFSName CONTAINS[c] "Some String")'

Upvotes: 5

Views: 9443

Answers (2)

Abhishek Jain
Abhishek Jain

Reputation: 4739

Swift 3.0

let predicate = NSPredicate(format: "NOT (%K CONTAINS[c] %@)", "someKey", "Some String")
let testArray: [Any] = [[ "someKey" : "This sure is Some String" ], [ "someKey" : "I've nothing to say" ], [ "someOtherKey" : "I don't even have that key" ]]
let filteredArray: [Any] = testArray.filter { predicate.evaluate(with: $0) }
print("found \(filteredArray)")

Upvotes: 1

Tommy
Tommy

Reputation: 100662

I had complete success with:

NSPredicate* predicate = [NSPredicate predicateWithFormat:@"NOT (%K CONTAINS[c] %@)",
        @"someKey",
        [NSString stringWithFormat:@"Some String"]];
NSArray *testArray =
    [NSArray arrayWithObjects:
        [NSDictionary dictionaryWithObject:@"This sure is Some String" forKey:@"someKey"],
        [NSDictionary dictionaryWithObject:@"I've nothing to say" forKey:@"someKey"],
        [NSDictionary dictionaryWithObject:@"I don't even have that key" forKey:@"someOtherKey"],
        nil];

NSArray *filteredArray = [testArray filteredArrayUsingPredicate:predicate];
NSLog(@"found %@", filteredArray);

The second two objects of the three in testArray ended up in filteredArray, under OS X v10.7 and iOS v4.3. So the issue isn't the predicate — making this technically a complete answer to the question — it's some sort of restriction in NSMetadataQuery. Sadly I've no experience in that area, but it's certainly the next thing to research.

Upvotes: 11

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