Replacing NSNulls inside NSDictionary - cocoa

Question

this question is similar to Replace occurrences of NSNull in nested NSDictionary
In swift I am getting an error (I believe because of NSNull's) I don't really care if the NSNull becomes an empty string or a nil. I am just wanting to get the code to work.
I have a large data structure coming in from JSON as an NSDictionary. Then I am saving that to a temporary file. Here is the code:
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.")
}
}
Here's an example of what jsonResult looks like
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>";
},

Answer 1

UPDATE:
Problem: I have a very large amount of JSON (roughly 600kb as text) Within that JSON data there are nulls. The problem I was having is that when you NSJSONSerialization as NSDictionary, it converts the nulls into NSNull objects (it looks funky if you print this out because they appear as a string, this is wrong.
Solution: You need to have a "pruned" or "sanitized" dictionary. What this means is to throw out the key and value entirely. To do this, I added a sanitized_dict function. Here is the function:
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
}
So your other code needs to call that function, it should look something like this:
var err: NSError?
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.")
}
}
Hope this helps somebody out there with a big JSON dataset and nulls. It is all about that sanitize function!