CoreData FetchRequest与可变形

Question

我正在尝试获取包含可转换类型TransType的对象CoreDataTypeA。我想获得与我传入NSPredicate的可转换类型相匹配的对象。当我返回下面的代码时，我总是得到0。

    let predicate = NSPredicate(format: "TransType == %@", transType)
    let fetchRequest : NSFetchRequest<CoreDataTypeA> = NSFetchRequest(entityName: "CoreDataTypeA")
    fetchRequest.fetchLimit = 1
    fetchRequest.sortDescriptors = [NSSortDescriptor(key: "timeStamp", ascending: false)]
    fetchRequest.predicate = predicate

    do {
        let requestReturn = try self.managedObjectContext.fetch(fetchRequest)
        guard requestReturn.count != 1 else {
            return 0.0 // Always returns THIS !!!!
        }

        let fetchedObj = requestReturn[0]
        print("object Value: \(fetchedObj.value)")
        return fetchedObj.objValue

    } catch {
        print("Error, not found!")
        return 0.0
    }

编辑：更改代码以删除guard语句以使其更容易：

    let predicate = NSPredicate(format: "TransType == %@", transType)
    let fetchRequest : NSFetchRequest<CoreDataTypeA> = NSFetchRequest(entityName: "CoreDataTypeA")
    fetchRequest.fetchLimit = 1
    fetchRequest.sortDescriptors = [NSSortDescriptor(key: "timeStamp", ascending: false)]
    fetchRequest.predicate = predicate

    do {
        let requestReturn = try self.managedObjectContext.fetch(fetchRequest)

    if(requestReturn.count != 0) {
        let fetchedObj = requestReturn[0]
        print("object Value: \(fetchedObj.value)")
        return fetchedObj.objValue
    } else {
        return 0.0 // STILL RETURNS HERE
    }

    } catch {
        print("Error, not found!")
        return 0.0
    }