core-dataswiftnspredicatenscompoundpredicate

Building an NSCompoundPredicate from array values in Swift

List item

So I'm trying to set up a request with multiple conditions in Swift. The SQL equivalent to:

select BOARDID
 from BOARD
 where BOARDID not like "someBoard"
 and BOARDID not like "anotherBoard"
 ..

I have an array of strings and I'm trying to iterate over each to create a subPredicate, add it to a compoundPredicate, then create a fetch request using that compoundPredicate:

let openBoards = ["someBoard", "anotherBoard", "etc"],
    request = NSFetchRequest(entityName: "Board")

var openBoardsSubPredicates: Array = [],
    error: NSError? = nil

for board in openBoards {
    var subPredicate = NSPredicate(format: "boardID not like '\(board)'")
    openBoardsSubPredicates += subPredicate
}

request.predicate = NSCompoundPredicate.andPredicateWithSubpredicates(openBoardsSubPredicates)

However, it fails at the var subPredicate line..

Thanks!

Solution

  • The error tells you what the problem is. The format you are providing is not a valid format. Specifically, there is no "not like" comparison. You have to do the "not" outside:

    NSPredicate(format: "not (boardID like %@)", board)

    As @MartinR mentioned below, you can have NSPredicate automatically escape special characters so they don't interfere with the predicate by having it insert the variable instead of using string interpolation.