Prefer For-Where

where clauses are preferred over a single if inside a for

• Identifier: for_where
• Enabled by default: Yes
• Supports autocorrection: No
• Kind: idiomatic
• Analyzer rule: No
• Minimum Swift compiler version: 5.0.0
• Default configuration:

  Key	Value
  severity	warning
  allow_for_as_filter	false

Non Triggering Examples

for user in users where user.id == 1 { }

for user in users {
  if let id = user.id { }
}

for user in users {
  if var id = user.id { }
}

for user in users {
  if user.id == 1 { } else { }
}

for user in users {
  if user.id == 1 {
  } else if user.id == 2 { }
}

for user in users {
  if user.id == 1 { }
  print(user)
}

for user in users {
  let id = user.id
  if id == 1 { }
}

for user in users {
  if user.id == 1 { }
  return true
}

for user in users {
  if user.id == 1 && user.age > 18 { }
}

for user in users {
  if user.id == 1, user.age > 18 { }
}

for (index, value) in array.enumerated() {
  if case .valueB(_) = value {
    return index
  }
}

//
// allow_for_as_filter: true
//

for user in users {
  if user.id == 1 { return true }
}

//
// allow_for_as_filter: true
//

for user in users {
  if user.id == 1 {
    let derivedValue = calculateValue(from: user)
    return derivedValue != 0
  }
}

Triggering Examples

for user in users {
  ↓if user.id == 1 { return true }
}

for subview in subviews {
    ↓if !(subview is UIStackView) {
        subview.removeConstraints(subview.constraints)
        subview.removeFromSuperview()
    }
}

//
// allow_for_as_filter: true
//

for subview in subviews {
    ↓if !(subview is UIStackView) {
        subview.removeConstraints(subview.constraints)
        subview.removeFromSuperview()
    }
}