Fail to change the label text with a timer in swift - ios

Question

As a swift beginner, I'm building a simple app which will get data from a website to update the label text.
In the ViewController.swift I begin with a function called requestCycle():
override func viewDidLoad() {
super.viewDidLoad()
requestCycle()
}
In this requestCycle() function I create a timer to call the http request function basicAuthHttpRequest():
func requestCycle(){
self.timer = Timer.scheduledTimer(timeInterval: 5, target: self, selector: #selector(ViewController.basicAuthHttpRequest), userInfo: nil, repeats: true);
RunLoop.current.add(self.timer, forMode: RunLoopMode.commonModes);
}
In the basicAuthHttpRequest() function, I set up an http request to get data from a url, and use the data to update the label text:
...
//http request, parse json, store the data in TempIn
let TempInString = String(describing: TempIn!)
self.TempInLabel.text = TempInString
print(TempInString)
print(self.TempInLabel.text!)
...
When I run the app, the data will be printed("33" and Optional("33")) and NO ERRORs occur. However, the text of the label shown is not changed at all.
If I use a button to trigger the function basicAuthHttpRequest(), after clicking the button, the label text will be changed in a few seconds.
What's wrong with my poor timer? =.=

Answer 1

You have to update text on the main thread.
DispatchQueue.main.async {
let TempInString:String = String(describing: TempIn!)
self.TempInLabel.text = TempInString as String
}

Answer 2

Try below code :-
DispatchQueue.main.async(execute: { self.TempInLabel.text = TempInString as String })

Answer 3

The timer is running on background thread. so you have to update label value with main thread. You have to use below code for the same.
self.performSelector(onMainThread: #selector(updateUI), with: nil, waitUntilDone: true)
func updateUI() {
print("here update your UI")
}
Also you can do with OperationQueue.
OperationQueue.main.addOperation({
print("here update your UI")
})