Refresh View After Data Changes - ios

Question

Im trying to make real time chat, It is going good but I have a problem.
I have added a subview to navigationController instead of title. I have an avatar, full name of user and status in this view like whatsapp. I have got user is online string from pusher service and I want to display it in my subview bottom of user full name like whatsapp. How can I refresh the view when I get online string from func onPresenceChanged(stateChange method ?
I have added self.navbar.setNeedsDisplay() but it is not working.
ChatViewController.swift (I cropped it for quick review)
class ChatViewController: UIViewController, UITextFieldDelegate, UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout, PCRoomDelegate {
var navbarView = UIView()
var navbarAvatar = UIImageView()
var navbar = UILabel()
var statusString = [String]()
var usernameString = [String]()
override func viewDidLoad() {
super.viewDidLoad()
self.navbarView = UIView(frame: CGRect(x: 0.0, y: 0.0, width: UIScreen.main.bounds.width / 1.4, height: 44.0))
self.navbarView.backgroundColor = UIColor.clear
self.navbar = UILabel(frame: CGRect(x: 44.0, y: 0.0, width: UIScreen.main.bounds.width / 1.4 - 44, height: 44.0))
self.navbar.backgroundColor = UIColor.clear
self.navbar.numberOfLines = 2
self.navbar.textAlignment = NSTextAlignment.left
let bodyText = NSMutableAttributedString(string: "Halil İbrahim YÜCE", attributes: [NSAttributedString.Key.font: UIFont.systemFont(ofSize: 16, weight: .bold)])
usernameString.append("\n#" + "halilyc")
bodyText.append(NSAttributedString(string: usernameString.last!, attributes: [NSAttributedString.Key.font: UIFont.systemFont(ofSize: 13), NSAttributedString.Key.foregroundColor : UIColor.gray]))
self.navbar.attributedText = bodyText
self.navbarView.addSubview(navbar)
self.navigationItem.titleView = self.navbarView
}
func onPresenceChanged(
stateChange: PCPresenceStateChange,
user: PCUser
) {
print("User \(user.displayName)'s presence changed to \(stateChange.current.rawValue)")
self.statusString.append(stateChange.current.rawValue)
self.navbar.setNeedsDisplay()
if statusString.count != 0 {
self.usernameString.append("\n#" + statusString.last!)
}
}
}

Answer 1

Assigning a string variable to a UILabel's attributedText property doesn't create a binding between that string and the label; you need to update attributedText if you want to see an updated value in your UI. Also, UI updates must be performed on the main thread; your update from the network will be delivered on a background thread.
Finally, I don't see any need to keep an array of statuses, you just need the most recent.
You can refactor to create a computed variable that provides the current user status text for your navigation bar.
It isn't clear how you are intending to display the display name, the username and the status (There are 3 things, but only 2 lines). I have just made it three lines and you can adapt as you require.
class ChatViewController: UIViewController, UITextFieldDelegate, UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout, PCRoomDelegate {
var navbarView: UIView!
var navbarAvatar: UIImageView!
var navbar: UILabel!
var status: String? {
didSet {
self.updateNavText()
}
var username: String? {
didSet {
self.updateNavText()
}
var displayName: String?
didSet {
self.updateNavText()
}
var statusText: NSAttributedString {
let text = NSMutableAttributedString(string: displayName ?? "", attributes: [NSAttributedString.Key.font: UIFont.systemFont(ofSize: 16, weight: .bold)])
if let username = self.username {
text.append("\n#\(username)")
}
if let status = self.status {
text.append("\n\(status)")
}
return text
}
override func viewDidLoad() {
super.viewDidLoad()
self.navbarView = UIView(frame: CGRect(x: 0.0, y: 0.0, width: UIScreen.main.bounds.width / 1.4, height: 44.0))
self.navbarView.backgroundColor = UIColor.clear
self.navbar = UILabel(frame: CGRect(x: 44.0, y: 0.0, width: UIScreen.main.bounds.width / 1.4 - 44, height: 44.0))
self.navbar.backgroundColor = UIColor.clear
self.navbar.numberOfLines = 2
self.navbar.textAlignment = NSTextAlignment.left
let bodyText = NSMutableAttributedString(string: "Halil İbrahim YÜCE", attributes: [NSAttributedString.Key.font: UIFont.systemFont(ofSize: 16, weight: .bold)])
self.updateNavText()
self.navbarView.addSubview(navbar)
self.navigationItem.titleView = self.navbarView
}
func onPresenceChanged(
stateChange: PCPresenceStateChange,
user: PCUser
) {
print("User \(user.displayName)'s presence changed to \(stateChange.current.rawValue)")
DispatchQueue.main.async {
self.status = stateChange.current.rawValue
}
}
func updateNavText() {
self.navbar.attributedText = self.statusText
}

Answer 2

You can manage things like:
First, create a function to set up your all UI objects adding on viewController's view or whatever you want to add. Call this method (like setupInitialLayout()) in viewDidLoad(). By calling this method in viewDidLoad(), because you just need to add components only once and you don't need to call this method again.
Now create another method in which write your all code like set your data whatever you want to display. Call this method (like setupData()) in viewWillAppear(). Also, you can call this method setupData() whenever you need like just user is online you are chatting with and you want to show as Online, just call this method only.