Swift 解析查询findobjectsinbackgroundwithblock，不带数据匹配条件，然后不执行闭包

我设计了PFQuery，使用findobjectsinbackgroundithblock从Parse.com读取数据，但是Parse.com没有数据匹配条件。但我不知道为什么程序在结束时没有回车->无效

let query = PFQuery(className: "Ordermaster")

query.whereKey("username", equalTo: currentUser!.username!)
query.addDescendingOrder("date")

query.findObjectsInBackgroundWithBlock{
    (objects: [PFObject]?, error: NSError?) -> Void in

    //why not execute here
    if error == nil && objects!.count > 0 {
        let object = objects![0]
        self.closeDateLabel.text = object.objectForKey("date") as? String
    } else {
        self.closeDateLabel.text = "Without data"
    }

}