SAFE CODING: if let & guard

In Swift, variables can be declared as optional using the '?' symbol, indicating they may be nil. To safely check and unwrap these optional variables, 'if let' and 'guard' statements are recommended. These methods are safer than explicitly unwrapping optionals using the '!' symbol, which should be avoided.

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Create a NavStack

Add a loadData function

onAppear will load the data which dispatch the function after 3 seconds.

What if diplayText has an empty value?

Then code won’t be working.

we have to say if displayText exist, it runs

add a loading indicator

Create a boolean

@State var isLoading: Bool = false

add isLoading inside the loadData functino

on Appear, is loading will be true, after three seconds, it runs the code and change the loading boolean to false

While it’s loading, we show progressView()

Simulate the user data in the app

Create a nil variable of currentUserID

@State var currentUserID: String? = nil

Lets make loadData works when they have an user ID

Use Guard to make the code safer

if currentUserID isn’t userID, it shows sign in text and stop the function by return. if there is a value, than run the rest of the code below.

Force the code

by adding ! at the end will force the code, but it will break the entire app.