swift - FetchedResultsController 使用谓词排除集合中包含的结果

Question

我正在尝试过滤 FetchedResultsController 中的项目以过滤掉特定的一组项目。这些发动机具有特定的字母名称，后跟数字。名称中可能的字母范围是从“A”到“O”。我希望能够根据另一个条件过滤掉名称从“D”到“O”的引擎。

我设置了一个常量“highPowerEngines”，它是包含这些字母的集合。由于该名称仅包含一个字母，因此我想排除包含 highPowerEngines 中任何字母的任何名称。到目前为止，这是我的代码，我正在处理的谓词包含在 FIXME 之后:

func configureFetchedResultsController() {
    let context = databaseController.getContext()
    let enginesFetchRequest = NSFetchRequest<Engine>(entityName: CoreData.engine)
    let highPowerEngines: Set =  ["D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O"]

    var predicate = NSPredicate()
    if currentStage == 1 && stages! == 1 {
        predicate = NSPredicate(format: "engineType == %@", EngineType.singleStage.rawValue)
    } else if currentStage < stages! {
        predicate = NSPredicate(format: "engineType == %@", EngineType.boosterStage.rawValue)
    } else {
        predicate = NSPredicate(format: "engineType == %@", EngineType.upperStage.rawValue)
    }

    var predicateArray:[NSPredicate] = [
        predicate
        ]
    // FIXME: Sort out highPowerEngines
    if !dPlusEngineIAP {
        if currentStage == 1 && stages! == 1 {
            predicate = NSPredicate(format: "NOT engineDesignation CONTAINS %@", highPowerEngines)
            predicateArray.append(predicate)
        }
    }

    let compoundPredicate = NSCompoundPredicate(andPredicateWithSubpredicates: predicateArray)
    enginesFetchRequest.predicate = compoundPredicate

    let primarySortDescriptor = NSSortDescriptor(key: CoreData.isMadeByName, ascending: true)
    let secondarySortDescriptor = NSSortDescriptor(key: CoreData.engineDesignation, ascending: true)
    enginesFetchRequest.sortDescriptors = [primarySortDescriptor, secondarySortDescriptor]


    self.fetchedResultsController = NSFetchedResultsController<Engine>(
        fetchRequest: enginesFetchRequest,
        managedObjectContext: context,
        sectionNameKeyPath: CoreData.isMadeByName,
        cacheName: nil)

    self.fetchedResultsController.delegate = self

}

Answer 1

使用 IN 而不是 CONTAINS

NOT (engineDesignation IN %@)

更新

既然您想排除除树字母之外的所有内容，为什么不将谓词翻转为包含而不是排除，例如

engineDesignation BEGINSWITH ‘A’ OR
engineDesignation BEGINSWITH ‘B’ OR
engineDesignation BEGINSWITH ‘C’