由于未捕获的异常'NSInvalidArgumentException'而终止应用程序，原因：'-[NSNull长度]：无法识别的选择器已发送到实例

Question

when I try to load a related field, I get this error: "*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSNull length]: unrecognized selector sent to instance"

I feel like it's caused by loading a collection of data that the compiler doesn't know what to do with.

Any help appreciated.

    func findPostsInGroup() {


    let whereClause = "GroupPostBelongsTo.objectId = 'B52F6BEA-79F8-A58B-FF15-AF840BCB2A00'"
    let dataQuery = BackendlessDataQuery()
    dataQuery.whereClause = whereClause
    print("hey")

    var error: Fault?
    let posts = self.backendless.persistenceService.find(Posts.ofClass(),
        dataQuery:dataQuery) as BackendlessCollection
     print("hey")

    if error == nil {
        for post in posts.data as! [Posts] {
            print("post class is \(post.PostText)")
            print("post class is \(post.objectId)")
            print(post.Author.name)


        }

    }

    else {
        print("Server reported an error: \(error)")
    }

}

import Foundation

Groups table class definition

    class Groups : NSObject{

    var groupName: String?
    var UsersInGroup = [BackendlessUser]()
    var ownerId: String?
    var objectId : String?

}

Answer 1

Yup, the post.Author.name was empty. Making sure it wasn't by adding a value for it fixed that. Thank you.