从'[PFObject]?‘下载？to '[PFObject]‘仅展开可选参数

Question

我正在将一个解析查询保存到一个数组中，但是我把下面的错误放在if let objects = objects as？PFObject

下面的错误从'PFObject?‘开始向下转换。to 'PFObject‘仅展开可选参数。

有人知道怎么解决这个问题吗？

​

func getArray(funcstring: String){
        
        var userGeoPoint: PFGeoPoint
        PFGeoPoint.geoPointForCurrentLocationInBackground {
            (geoPoint: PFGeoPoint?, error: NSError?) -> Void in
            if error == nil {
        
            userGeoPoint = geoPoint!
            }
        }
        
        
        var searchQuery: [String] = [String]()
        
        var query = PFQuery(className:"User")
        query.whereKey("geoLocation", nearGeoPoint:userGeoPoint)
        query.limit = 100
        query.findObjectsInBackgroundWithBlock {
            (objects: [PFObject]?, error: NSError?) -> Void in
            if error == nil {
                if let objects = objects as? [PFObject] {
                    for object in objects {
                        self.searchQuery.append(object.objectForKey("objectId") as! String)
                        
                    }
                    
                }
            } else {
                print("\(error?.userInfo)")
            }
        }

        
        
        
        
                }

​

Answer 1

objects被声明为[PFObject]?。

您将把对象向下转换为编译器已经知道的内容。

只需检查nil

if let unwrappedObjects = objects {
  for object in unwrappedObjects {
     self.searchQuery.append(object.objectForKey("objectId") as! String)    
  }
}

还是“更快”？

if let unwrappedObjects = objects {
   self.searchQuery = unwrappedObjects.map{ $0["objectId"] as! String }   
}