Cocoa 在NSDictionary中替换NSNulls

这个问题类似于

在swift中，我得到了一个错误（我相信是因为NSNull），我并不在乎NSNull是变成空字符串还是nil。我只是想让代码正常工作

我有一个来自JSON的大型数据结构作为NSDictionary。然后我将它保存到一个临时文件中。代码如下：

var jsonResult = NSJSONSerialization.JSONObjectWithData(data, options: .MutableContainers, error: &err) as! NSDictionary

let json = JSON(jsonResult)

if (json["errors"].array?.count > 0) {
                println("could not load stuff")
            } else {
                println("retrieving the stuff")

                let file = "file.txt"
                let file_path = NSTemporaryDirectory() + file
                let dict:NSDictionary = jsonResult
                let readDict:NSDictionary? = NSDictionary(contentsOfFile: file_path)

                    if dict.writeToFile(file_path, atomically: true) {
                        let readDict:NSDictionary? = NSDictionary(contentsOfFile: file_path)

                        //--- need to handle the NSNull junk here


                        if let dict = readDict {
                            println("Temp file created, here are the contents: \(dict)")
                        } else {
                            println("!!!Failed to READ the dictionary data back from disk.")
                        }
                    }
                    else {
                        println("!!!Failed to WRITE the dictionary to disk.")
                    }
                }

下面是一个jsonResult的示例

things = (
  {
                "one" = one;
                two = "<null>";
                "three" = three;
                "four" = "<null>";
                "five" = five;
                "six" = "six-6";
                seven = 7;
                eight = eight;
                nine = "<null>";
                ten = "<null>";
                eleven = "<null>";
                "twelve" = "<null>";
            },

事物=(
{
“一”=一；
两个“”；
“三”=三；
“四”=”；
“五”=五；
“六”=“六-6”；
七=7；
八=八；
“九”；
“十”；
11=“”；
“十二”；
},

更新：

问题：我的JSON数据中有大量的JSON（大约600kb为文本），其中有空值。我遇到的问题是，当您将NSJSONSerialization作为NSDictionary时，它会将空值转换为NSNull对象（如果您将其打印出来，因为它们显示为字符串，这看起来很奇怪，这是错误的）

解决方案：您需要一个“删减”或“净化”字典。这意味着完全丢弃键和值。为此，我添加了一个净化的dict函数。函数如下：

func sanitize_dict(obj: AnyObject) -> AnyObject {

    if obj.isKindOfClass(NSDictionary) {

        var saveableObject = obj as! NSMutableDictionary

        for (key, value) in obj as! NSDictionary {

            if (value.isKindOfClass(NSNull)) {

                //println("Removing NSNull for: \(key)")

                saveableObject.removeObjectForKey(key)

            }

            if (value.isKindOfClass(NSArray)) {

                let tmpArray: (AnyObject) = sanitize_dict(value as! NSArray)

                saveableObject.setValue(tmpArray, forKey: key as! String)

            }

            if (value.isKindOfClass(NSDictionary)) {

                let tmpDict: (AnyObject) = sanitize_dict(value as! NSDictionary)

                saveableObject.setValue(tmpDict, forKey: key as! String)

            }

        }

        return saveableObject



    //--- because arrays are handled differently,

    //--- you basically need to do the same thing, but for an array

    //--- if the object is an array

    } else if obj.isKindOfClass(NSArray) {

        var saveableObject = [AnyObject]()

        for (index, ele) in enumerate(obj as! NSArray) {

            if (ele.isKindOfClass(NSNull)) {

                // simply don't add element to saveableobject and we're good

            }

            if (ele.isKindOfClass(NSArray)) {

                let tmpArray: (AnyObject) = sanitize_dict(ele as! NSArray)

                saveableObject.append(tmpArray)

            }

            if (ele.isKindOfClass(NSDictionary)) {

                let tmpDict: (AnyObject) = sanitize_dict(ele as! NSDictionary)

                saveableObject.append(tmpDict)

            }

        }

        return saveableObject

    }



    // this shouldn't happen, but makes code work

    var saveableObject = [AnyObject]()

    return saveableObject

}

因此，您的其他代码需要调用该函数，它应该如下所示：

变量错误：n错误

        var jsonResult = NSJSONSerialization.JSONObjectWithData(data, options: .MutableContainers, error: &err) as! NSDictionary

        //--- right now jsonResult is not actual json, and actually has the NSNulls

        //--- get that result into the sanitized function above

        let saveableDict: (AnyObject) = self.sanitize_dict(jsonResult)

        let json = JSON(saveableDict)



        if (json["errors"].array?.count > 0) {

            println("!!!Failed to load.")

        } else {

            println("Load json successful. Attempting to save file...")



            //--- set up basic structure for reading/writing temp file

            let file = "file.txt"

            let file_path = NSTemporaryDirectory() + file

            let dict:NSDictionary = jsonResult

            let readDict:NSDictionary? = NSDictionary(contentsOfFile: file_path)



                if dict.writeToFile(file_path, atomically: true) {

                    let readDict:NSDictionary? = NSDictionary(contentsOfFile: file_path)



                    if let dict = readDict {

                        println("Temp file created, here are the contents: \(dict)")

                    } else {

                        println("!!!Failed to READ the dictionary data back from disk.")

                    }

                }

                else {

                    println("!!!Failed to WRITE the dictionary to disk.")

                }

            }

---

希望这能在JSON数据集和空值方面对其他人有所帮助。这都是关于清理功能的！

“在swift中，我遇到了一个错误（我相信是因为NSNull的错误）”–你为什么这么认为？JSON看起来像什么？你会得到什么错误？@Martinar看着jsonResult，看起来这就是问题所在。有没有办法强制所有东西都是字符串？我知道因为writeFile，所有的键都必须是字符串。我在主帖子中放了一个jsonResult看起来像什么的示例。我是also前一段时间收到“致命错误：在展开可选值时意外发现nil”（出于某种原因，我不再收到该错误）