[FetchPropertiesOnDemand] Fetch part of properties in an managed object #CoreData #Fetch

readme.txt

When you don't want to get all propeties form a managed object, then use this sample code to get part of properties you want.

FetchPropertiesOnDemand.swift

let briefInfoFetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "ClothItem")
briefInfoFetchRequest.resultType = .dictionaryResultType
briefInfoFetchRequest.returnsObjectsAsFaults = false

let desc = NSExpressionDescription()
desc.name = "mainPhoto"
desc.expression = NSExpression(forKeyPath: "mainPhotoURLString")
desc.isStoredInExternalRecord = true
desc.expressionResultType = .stringAttributeType


briefInfoFetchRequest.propertiesToFetch = ["name", desc]

do {
    itemBriefInfoArray = try managedContext!.fetch(briefInfoFetchRequest)
    print(itemBriefInfoArray)
}catch let error as NSError {
    print("Fetch item failed:\(error), \(error.userInfo)")
}