Swift; Initialization of immutable value was never used

Question

I have this simple piece of Swift code:

let message = "This is a test"

if message.range(of:"test") != nil {
    let message = "Changed string"
}

print(message)

What I want to do: If string message contains the string test, change it to Changed string. Else keep it unchanged.

I'm getting the following warning:

Initialization of immutable value 'message' was never used; consider replacing with assignment to '_' or removing it

for line

let message = "Changed string"

Also, printed output is still This is a test instead of expected Changed string.

What am I doing wrong?

Answer 1

If you want it to change it, you should be making it a variable and using the same variable.

var message = "This is a test"

if message.range(of:"test") != nil {
    message = "Changed string"
}

print(message)