override open func prepare() {
        guard let collectionView = collectionView else {
            return
        }
        

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

    }

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
}

    override open var collectionViewContentSize : CGSize {

Close

colon-whitespace

There should be no whitespace preceding the colon, exactly one whitespace after the colon for: * var, class, struct, protocol, extension, func, and tuple declarations * dict literals and types * case statements

However, for conditional expressions there should be a single whitespace before and after the colon.

Variable declarations

Preferred

var x: Int = 2

Not Preferred

var x : Int
var y:   String

Dictionary literals and types

Preferred

var x = [ 'key1': 1, 'key2': 2 ]
var y: [ Int: String ]

Not Preferred

var x = [ 'key1' : 1, 'key2':  3]
var y: [ Int :    String ]

Case statements

Preferred

switch character {
case "a": doSomething(a);
default: alert();
}

Not Preferred

switch character {
case "a" : doSomething(a);
default:     alert();
}

Class, Struct, Protocol, and Extension declarations

Preferred

class ClassName: BaseClass {
}

struct StructName: BaseStruct {
}

protocol ProtocolName: AnotherProtocol {
}

extension TypeName: ProtocolName {
}

Not Preferred

class ClassName : BaseClass {
}

struct StructName:  BaseStruct {
}

protocol ProtocolName:AnotherProtocol {
}

extension TypeName : ProtocolName {
}

Tuple declarations

Preferred

var y = (key: 1, value: 2)

Not Preferred

var y = (key:1, value : 2)

Function declarations

Preferred

func someFunction<t: someclass u: someprotocol>(someT: T, someU: U) {
}</t:>

Not Preferred

func someFunction<t : someclass u:someprotocol>(someT: T, someU: U) {
}</t>

Conditional expressions

Preferred

var x = condition ? a : b

Not Preferred

var x = condition ? a: b
var x = condition ? a   : b