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Saving KCSUser as a property

I have a class call Newsfeed and every newsfeed object contains a variable called author of type KCSUser. whenever I try creating a user. I get the following exception

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Invalid type in JSON write (KCSUser)'

This is my Newsfeed Class.  I'm not sure why i'm getting this exception cause according to documentation, I should be able to save a KCSUser.

class Newsfeed: NSObject {

var entityId: String?

var authorImageUrl: String?

var authorFullName: String?

var authorUserId: String?

var author: KCSUser?

var attachments: [String]?

var attachmentType: Int = 0

var viewCount: Int = 0

var message: String?

var metadata: KCSMetadata?

override func hostToKinveyPropertyMapping() -> [NSObject : AnyObject]! {

return [

"entityId" : KCSEntityKeyId,

"authorImageUrl" : "authorImageUrl",

"authorFullName" : "authorFullName",

"authorUserId" : "authorUserId",

"author" : "author",

"attachments" : "attachments",

"attachmentType": "attachmentType",

"viewCount" : "viewCount",

"message" : "message",

"metadata" : KCSEntityKeyMetadata



static override func kinveyPropertyToCollectionMapping() -> [NSObject : AnyObject]! {

return [

"author" : KCSUserCollectionName,




I figured out why I was getting this issue. I was using KCSAppdataStore instead of KCSLinkedAppdataStore after using KCSLinkedAppdataStore, i'm getting similar error but for KCSKinveyRef.

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Invalid type in JSON write (KCSKinveyRef)'

this is the saving code.

class func saveObject(collectionName collectionName: String,

collectionClass: AnyClass,

collectionObj: AnyObject,

linkedAppDataSotre: Bool,

saveBlock: SaveBlock,

progressBlock: ProgressBlock?) {

var store: KCSAppdataStore

let collection = KCSCollection(fromString: collectionName, ofClass: collectionClass.self)

if linkedAppDataSotre == true {

store = KCSLinkedAppdataStore(collection: collection, options: nil)

} else {

store = KCSAppdataStore(collection: collection, options: nil)


store.saveObject(collectionObj, withCompletionBlock: { (response, error) -> Void in

saveBlock(response: response, error: error)

}) { (response, percentCompleted) -> Void in

if let progress = progressBlock {

progress(response: response, percentCompleted: percentCompleted)




Can someone help please, because I really need to be able to have relational model.  Right now i'm stuck and can't do much without resolving this issue.

3 people like this

Exactly the same problem! Someone please help, this stuff was so easy with Parse and worked instantly on Backendless, why won't it work here?

Steeven, Addy,

At this time this is being looked at as a bug in our codebase.   We apologize for the inconvenience that this is clearly causing and will hopefully release an updated SDK in the next few days to address this.


2 people like this

Hey Damien, thank you for looking into this.

Require this for me app as well

@Damien we're counting on you guys....  we're still waiting for the updated SDK

1 person likes this


Our development sprint wraps up this coming Wednesday, so I would anticipate seeing it by close of business on Wednesday or sooner.  I will update this thread when we release the update.


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@Damien, any updates on the fix?

Also, if there is an earlier library that I can use (proven to be working) in the mean time, please let me know. 

Hello all,

We have released an update to the iOS library (1.40.5) which is available over here:


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