How to elegantly combine a guard statement with a condition?

Question

I currently have the guard statement:

 guard let designationQuota = Defaults.quotas.value?.designationQuota, designationQuota > 0 else {
      return AppDelegate.shared.presentNoDesignationQuotaWarning()
 }

however I only want to do the guard block if the variable needsQuota == true. I want to skip the guard statement if needsQuota == false. Is there a nicer way of doing this over than an if statement with a return?

EDIT:

How do I simplify this into a single guard?

if needsQuota {
  guard let designationQuota = Defaults.quotas.value?.designationQuota, designationQuota > 0 else {
      return AppDelegate.shared.presentNoDesignationQuotaWarning()
   }
}

What variable `needsQuota`, what am I missing here? – Joakim Danielson Jan 10 '19 at 11:46 — Joakim Danielson, Jan 10 '19 at 11:46

ielyamani · Answer 1 · 2019-01-10T12:09:42.360

1

How about :

guard !needsQuota ||
    (Defaults.quotas.value?.designationQuota.map { $0 > 0 } == true) else {
    return AppDelegate.shared.presentNoDesignationQuotaWarning()
}

edited Jan 10 '19 at 12:09

answered Jan 10 '19 at 11:48

ielyamani

17,807
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@MartinR Yes :p This feels more like a yoga pose – ielyamani Jan 10 '19 at 12:08

Dávid Pásztor · Answer 2 · 2019-01-10T12:11:54.820

The problem is that you want to continue execution differently in case your if condition fails or in case your guard fails, so you cannot really combine them into a single guard. However, you could combine the two conditions into an if statement by putting the negated version of your guard condition in the if statement.

if needsQuota && (Defaults.quotas.value?.designationQuota ?? 0 <= 0) {
    return AppDelegate.shared.presentNoDesignationQuotaWarning()
}

score 0 · Answer 3 · answered Jan 10 '19 at 15:12

0

Wouldn‘t this do the trick?

guard needsQuota, let designationQuota = Defaults.quotas.value?.designationQuota, designationQuota > 0 else {
    return AppDelegate.shared.presentNoDesignationQuotaWarning()
}

answered Jan 10 '19 at 15:12

henrik-dmg

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How to elegantly combine a guard statement with a condition?

3 Answers3