Guard in a conditional statement

Question

Depending on the value of the

units

parameter, I would like to unwrap the Fahrenheit or Celsius temperature using

guard

. However, I get an error about

Use of unresolved identifier 'temp'

from the following example code

let units = 0



if units == 0 {

  guard let temp = currentDict["temp_f"] as? String else { return nil }

} else {

  guard let temp = currentDict["temp_c"] as? String else { return nil }

}

Why does

guard

not work in this example?

Answer 1

It doesn't work because temp was scoped to be within the if statement only. Try this instead:

let key = units == 0 ? "temp_f" : "temp_c"
guard let temp = currentDict[key] as? String else { return nil }

Guard in a conditional statement

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