Unused Closure Parameter

Unused parameter in a closure should be replaced with _.

• Identifier: unused_closure_parameter
• Enabled by default: Enabled
• Supports autocorrection: Yes
• Kind: lint
• Analyzer rule: No
• Minimum Swift compiler version: 3.0.0
• Default configuration: warning

Non Triggering Examples

[1, 2].map { $0 + 1 }

[1, 2].map({ $0 + 1 })

[1, 2].map { number in
 number + 1 
}

[1, 2].map { _ in
 3 
}

[1, 2].something { number, idx in
 return number * idx
}

let isEmpty = [1, 2].isEmpty()

violations.sorted(by: { lhs, rhs in 
 return lhs.location > rhs.location
})

rlmConfiguration.migrationBlock.map { rlmMigration in
return { migration, schemaVersion in
rlmMigration(migration.rlmMigration, schemaVersion)
}
}

genericsFunc { (a: Type, b) in
a + b
}

var label: UILabel = { (lbl: UILabel) -> UILabel in
   lbl.backgroundColor = .red
   return lbl
}(UILabel())

hoge(arg: num) { num in
  return num
}

({ (manager: FileManager) in
  print(manager)
})(FileManager.default)

withPostSideEffect { input in
    if true { print("\(input)") }
}

viewModel?.profileImage.didSet(weak: self) { (self, profileImage) in
    self.profileImageView.image = profileImage
}

Triggering Examples

[1, 2].map { ↓number in
 return 3
}

[1, 2].map { ↓number in
 return numberWithSuffix
}

[1, 2].map { ↓number in
 return 3 // number
}

[1, 2].map { ↓number in
 return 3 "number"
}

[1, 2].something { number, ↓idx in
 return number
}

genericsFunc { (↓number: TypeA, idx: TypeB) in return idx
}

hoge(arg: num) { ↓num in
}

fooFunc { ↓아 in
 }

func foo () {
 bar { ↓number in
 return 3
}

viewModel?.profileImage.didSet(weak: self) { (↓self, profileImage) in
    profileImageView.image = profileImage
}