如何检查核心数据是否为空

如何使用 swift检查核心数据是否为空.我试过这个方法：

var people = [NSManagedobject]()

if people == nil {

}

但这会导致此错误

“binary operator ‘==’ cannot be applied to operands of type [NSManagedobject] and nil”

要检查核心数据库是否为空,您必须在要检查的实体上进行NSFetchRequest,并检查请求的结果是否为空.

您可以使用此功能进行检查：

func entityIsEmpty(entity: String) -> Bool
{

    var appDel:AppDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
    var context = NSManagedobjectContext()

    var request = NSFetchRequest(entityName: entity)
    var error = NSErrorPointer()

    var results:NSArray? = self.context.executeFetchRequest(request,error: error)

    if let res = results
    {
        if res.count == 0
        {
            return true
        }
        else
        {
            return false
        }
    }
    else
    {
        println("Error: \(error.debugDescription)")
        return true
    }

}

或简化和更短的解决方案:(使用.countForFetchRequest)

func entityIsEmpty(entity: String) -> Bool
{

    var appDel:AppDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
    var context = NSManagedobjectContext()

    var request = NSFetchRequest(entityName: entity)
    var error = NSErrorPointer()

    var results:NSArray? = self.context.executeFetchRequest(request,error: error)

    var count = context.countForFetchRequest(request,error: error)

    if error != nil
    {
        println("Error: \(error.debugDescription)")
        return true
    }
    else
    {
        if count == 0
        {
            return true
        }
        else
        {
            return false
        }

    }


}