Segue using tableViewCells - ios

Question

I am going to try to be as clear as I can be on this question but if you need more information please please ask. I have a tableviewcontroller that has a list of all the messages the logged in user has had with other users of the app. When clicked the logged in user clicks a cell, I would like for the user to segue to a view controller that allows them to chat with whatever user they like. This chat was acquired using JSQMessageController. However, when I set it the segue in the tableviewcontroller, show below:
override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
let message = messages[indexPath.row]
if message.ReceiverId != self.loggedInUserUid {
var newVariable = message.ReceiverId
if self.userpicuid == newVariable {
let ref = FIRDatabase.database().reference().child("users").child(userpicuid!)
ref.observeSingleEvent(of: .value, with: { (snapshot)
in
if let dictionary = snapshot.value as? [String: AnyObject]{
for post in dictionary {
let messages = post.value as! [String: AnyObject]
for (id, value) in messages {
self.username = messages["username"] as? String
}}}})}} else if message.senderId != self.loggedInUserUid {
let newVariable = message.senderId
if self.userpicuid == newVariable {
let ref = FIRDatabase.database().reference().child("users").child(userpicuid!)
ref.observeSingleEvent(of: .value, with: { (snapshot)
in
if let dictionary = snapshot.value as? [String: AnyObject]{
for post in dictionary {
let messages = post.value as! [String: AnyObject]
for (id, value) in messages {
self.username = messages["username"] as? String
}}}})}
}
performSegue(withIdentifier: "MessageNow", sender: self.userpicuid)
}
override public func prepare(for segue: UIStoryboardSegue, sender: Any?) {
guard segue.identifier == "MessageNow", let chatVc = segue.destination as? SendMessageViewController else {
return
}
chatVc.senderId = self.loggedInUser?.uid
chatVc.receiverData = sender as AnyObject
chatVc.senderDisplayName = self.userpicuid
chatVc.username = self.username
}
I get an error in the MessageViewController:
var receiverData: AnyObject?
override func viewDidLoad() {
super.viewDidLoad()
let receiverId = receiverData as! String
let receiverIdFive = String(receiverId.characters.prefix(5))
let senderIdFive = String(senderId.characters.prefix(5))
if (senderIdFive > receiverIdFive)
{
self.convoId = senderIdFive + receiverIdFive
}
else
{
self.convoId = receiverIdFive + senderIdFive
}}
I get the error on the let receiverId = receiverData as! String that:
Could not cast value of type 'Chat_App.MessageTableViewCell' (0x10eb2ef10) to 'NSString' (0x110ab1c60).
in a different view controller, I have:
#IBAction func sendMessage(_ sender: Any) {
performSegue(withIdentifier: "sendMessageToUser", sender: self.userpicuid)
}
override public func prepare(for segue: UIStoryboardSegue, sender: Any?) {
guard segue.identifier == "sendMessageToUser", let chatVc = segue.destination as? SendMessageViewController else {
return
}
chatVc.senderId = self.loggedInUser?.uid
chatVc.receiverData = sender as! String!
chatVc.senderDisplayName = self.userpicuid
chatVc.username = self.username
}
And it segues perfectly.

Answer 1

Sender is Any? and you're casting it to AnyObject. AnyObject refers to a class type, and it's asserting when you attempt to cast it to a Swift value type (String).
Try this instead:
chatVc.receiverData = NSString(string: sender as! String)

Answer 2

Your sender is the the UITableViewCell that initiated the segue. You are crashing when casting it to NSString. Remove this line
let receiverId = receiverData as! String
In prepareForSegue do this instead
chatVc.receiverData = self.userpicuid