internal func filter(predicate: NSPredicate) -> AnyRandomAccessCollection<Iterator.Element> {
        #if !os(watchOS)
            if let (_, keyPathConstantTuple, constantValue) = tupleMKShape(predicate: predicate) {
                if let circle = constantValue as? MKCircle {
                    let center = CLLocation(latitude: circle.coordinate.latitude, longitude: circle.coordinate.longitude)

Close

Cognitive Complexity

Cognitive Complexity is a measure of how difficult a unit of code is to intuitively understand. Unlike Cyclomatic Complexity, which determines how difficult your code will be to test, Cognitive Complexity tells you how difficult your code will be to read and comprehend.

A method's cognitive complexity is based on a few simple rules:

• Code is not considered more complex when it uses shorthand that the language provides for collapsing multiple statements into one
• Code is considered more complex for each "break in the linear flow of the code"
• Code is considered more complex when "flow breaking structures are nested"

Further reading

• Cognitive Complexity docs
• Cognitive Complexity: A new way of measuring understandability

                    return AnyRandomAccessCollection(filter({ (item) -> Bool in

Close

trailing-closure

Closures that are the last argument of a function should be passed into the function using trailing closure syntax.

Preferred

reversed = names.sort { s1, s2 in return s1 > s2 }

Not Preferred

reversed = names.sort({ s1, s2 in return s1 > s2 })

        {

Close

brace-style

Definitions of - class - struct - function - Control flow constructs (if, else if, else, switch, for, while, repeat-while) - init - protocol - enum - closure - Getters and Setters (set, get) - extension

should follow the One True Brace Style (1TBS): each construct has its opening brace one the same line along with the same indentation level as its header, the statements within the braces are indented, and the closing brace at the end is on the same indentation level as the header of the function at a line of its own. Braces are not omitted for a control statement with only a single statement in its scope. Every opening brace must also have one space preceding it.

Classes

Preferred

class SomeClass {
}

class SomeClass: SomeSuperClass {
}

Not Preferred

class SomeClass
{
}

class SomeClass: SomeSuperClass{
}

Structs

Preferred

struct SomeStruct {
}

struct SomeStruct : SomeParentStruct {
}

Not Preferred

struct SomeStruct
{
}

struct SomeStruct : SomeParentStruct  {
}

Functions

Preferred

func someMethod() {
}

func someOtherFunction () -> () {
}

Not Preferred

func someMethod()
{
}

func someOtherFunction () -> ()
{
}

Control flow constructs

• if, else if, and else statement

Preferred

if SomeCondition {

} else if someOtherCondition {
} else {
}

Not Preferred

if SomeCondition
{

}
else if someOtherCondition
{
}
else
{
}

• switch statement

Preferred

switch SomeData {
    default:
        break
}

Not Preferred

switch SomeData
{
    default:
        break
}

• for loop

Preferred

for var i = 0; i < 10; i+=1 {

}

Not Preferred

for var i = 0; i < 10; i+=1
{

}

• while loop

Preferred

while SomeCondition {

}

Not Preferred

while SomeCondition
{

}

• repeat-while loop

Preferred

repeat {

} while SomeCondition

Not Preferred

repeat
{

} while SomeCondition

Initializers

Preferred

init(someParameter:Double, someOtherParameter:Double) {
   self.someMember = someParameter
   self.someOtherMember = someOtherParameter
}

Not Preferred

init(someParameter:Double, someOtherParameter:Double)
{
   self.someMember = someParameter
   self.someOtherMember = someOtherParameter
}

Protocols

Preferred

protocol SomeProtocol {

}

protocol SomeOtherProtocol : X {

}

Not Preferred

protocol SomeProtocol
{

}

protocol SomeOtherProtocol : X
{
}

Enums

Preferred

enum SomeEnum {
    case A, B, C, D
}

enum SomeEnum {
    case A
    case B
    case C
    case D
}

enum SomeEnum: Int {
    case A, B, C = 5, D
}

Not Preferred

enum SomeEnum
{
    case A, B, C, D
}

enum SomeEnum
{
    case A
    case B
    case C
    case D
}

enum SomeEnum: Int
{
    case A, B, C = 5, D
}

Closures

Preferred

func someFunction () -> () {
// closure
}

Not Preferred

func someFunction () -> ()
{
// closure
}

Setters and Getters

• set

Preferred

set {
    oldValue = newValue / 2
}

Not Preferred

set
{
    oldValue = newValue / 2
}

• get

Preferred

get {
    return value * 2
}

Not Preferred

get
{
    return value * 2
}

Extensions

Preferred

extension someExtension {
}

Not Preferred

extension someExtension
{
}

    }

Close

function-whitespace

Every function and method declaration should have one blank line before and after itself. An exception to this rule are functions that are declared at the start of a file (only need one blank line after their declaration) or at the end of a file (only need one blank line before their declaration). Comments immediately before a function declaration (no blank lines between them and the function) are considered to be part of the declaration.

Preferred

func function1() {
  var text = 1
  var text = 2
}

function1()

// a comment
func function2() {
  // something goes here
}

struct SomeStruct {

  func function3() {
    // something goes here
  }

  func function4() {
    // something else goes here
  };

}

func function5() {
  // something goes here
}

Not Preferred

func function1() {
  var text = 1
  var text = 2
}
function1()
// a comment
func function2() {
  // something goes here
}

struct SomeStruct {
  func function3() {
    // something goes here
  }

  func function4() {
    // something else goes here
  };
}
func function5() {
  // something goes here
}

Close

trailing-whitespace

Flag whitespace after the last non-whitespace character on each line until the newline.

Preferred

let number = 42¬

Not Preferred

let number = 42••¬

    internal func tupleMKShape(predicate: NSPredicate) -> (NSComparisonPredicate, (keyPathExpression: NSExpression, constantValueExpression: NSExpression), Any)? {

Close

function-whitespace

Every function and method declaration should have one blank line before and after itself. An exception to this rule are functions that are declared at the start of a file (only need one blank line after their declaration) or at the end of a file (only need one blank line before their declaration). Comments immediately before a function declaration (no blank lines between them and the function) are considered to be part of the declaration.

Preferred

func function1() {
  var text = 1
  var text = 2
}

function1()

// a comment
func function2() {
  // something goes here
}

struct SomeStruct {

  func function3() {
    // something goes here
  }

  func function4() {
    // something else goes here
  };

}

func function5() {
  // something goes here
}

Not Preferred

func function1() {
  var text = 1
  var text = 2
}
function1()
// a comment
func function2() {
  // something goes here
}

struct SomeStruct {
  func function3() {
    // something goes here
  }

  func function4() {
    // something else goes here
  };
}
func function5() {
  // something goes here
}

Close

trailing-whitespace

Flag whitespace after the last non-whitespace character on each line until the newline.

Preferred

let number = 42¬

Not Preferred

let number = 42••¬

                    return AnyRandomAccessCollection(filter({ (item) -> Bool in

Close

trailing-closure

Closures that are the last argument of a function should be passed into the function using trailing closure syntax.

Preferred

reversed = names.sort { s1, s2 in return s1 > s2 }

Not Preferred

reversed = names.sort({ s1, s2 in return s1 > s2 })