无法分配“字符串”类型的值？ 输入“用户？”

Question

I try to perform a segue from a button to a specific userID chatController with this code:

@IBAction func toChatPressed(_ sender: Any) {
    let user = jobDetails?.userID
    let chatLogController = ChatLogController(collectionViewLayout: UICollectionViewFlowLayout())
    chatLogController.user = user
    navigationController?.pushViewController(chatLogController, animated: true)
}

But its giving me Cannot assign value of type 'String?' to type 'User?' as an error...

chatController.user:

var user: User? {
    didSet {
        navigationItem.title = user?.name
        observeMessages()
    }
}

I get the userID passed from a tableViewCell and is saved in a structure

struct JobDetails {
    var jobDetail: String
    var userName: String
    var userImage: UIImage?
    var jobImage: UIImage?
    var downloadURL: String?
    var userLocation: String
    var userID: String?
}

Answer 1

In chatController , the property user is of type User , ie

var user: User? {
    ....
}

Now, in toChatPressed(_:) method, you're setting the value of userID to chatController's user as evident from your code,

let user = jobDetails?.userID 

Here userID is a String? . So, user in the above code is of type String?

chatLogController.user = user 

In the above code, you are assigning user (of type String? ) to chatLogController.user (of type User ). This is what your error means.

Solution:

There can be 2 options to resolve the issue.

1. Either create a property userID of type String? in chatLogController , ie

var userID: String?

Now, set it from toChatPressed(_:) like,

chatLogController.userID = jobDetails?.userID

2. Or, you can create a User object using jobDetails in toChatPressed(_:) and then set it to chatLogController's user , ie

let user = User(jobDetails) //this depends upon the how you've defined User
chatLogController.user = user

In case you still have any confusion, feel free to ask.

Answer 2

You are assigning JobDetails.userID: String? to ChatLogController.user: User?

See your code:

    let user = jobDetails?.userID
    …
    chatLogController.user = user

You have to map the jobDetails?.userID: String to a User? .

Answer 3

Inside of your struct JobDetails , add a new field containing the User object:

struct JobDetails {
    var jobDetail: String
    var userName: String
    var userImage: UIImage?
    var jobImage: UIImage?
    var downloadURL: String?
    var userLocation: String
    var userID: String?
    var user: User? // <-- New field
}

Whenever you create a new JobDetails , pass the User object to the user field.

Now, you function can use the user field instead of the userID field:

@IBAction func toChatPressed(_ sender: Any) {
    let user = jobDetails?.user // <-- user of type User? instead of userID of type String?
    let chatLogController = ChatLogController(collectionViewLayout: UICollectionViewFlowLayout())
    chatLogController.user = user
    navigationController?.pushViewController(chatLogController, animated: true)
}