a method of determining whether the value of a variable has increased or decreased

I'd like to implement it on Swift, but any language is fine as long as logic is applied. The value (numeric) of a variable changes dynamically, but I'd like to branch the process by whether the value of that variable has increased or decreased.The code looks like the one below.

 if (variable value increased) {

print("Variable value increased!")

}esle if {

print("The value of the variable has decreased!")

}

I can't think of a way to implement it.I would appreciate your advice