Prefer Type Checking

Prefer a is X to a as? X != nil

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

Non Triggering Examples

let foo = bar as? Foo

bar is Foo

2*x is X

if foo is Bar {
    doSomeThing()
}

if let bar = foo as? Bar {
    foo.run()
}

bar as Foo != nil

nil != bar as Foo

bar as Foo? != nil

bar as? Foo? != nil

Triggering Examples

bar ↓as? Foo != nil

2*x as? X != nil

if foo ↓as? Bar != nil {
    doSomeThing()
}

nil != bar ↓as? Foo

nil != 2*x ↓as? X