AccessControl.md

Table of contents

• Access Control
• - Modules and Source Files
• - Access Levels
• - - Guiding Principle of Access Levels
• - - Default Access Levels
• - - Access Levels for Single-Target Apps
• - - Access Levels for Frameworks
• - - Access Levels for Unit Test Targets
• - Access Control Syntax
• - Custom Types
• - - Tuple Types
• - - Function Types
• - - Enumeration Types
• - - Nested Types
• - Subclassing
• - Constants, Variables, Properties, and Subscripts
• - - Getters and Setters
• - Initializers
• - - Default Initializers
• - - Default Memberwise Initializers for Structure Types
• - Protocols
• - - Protocol Inheritance
• - - Protocol Conformance
• - Extensions
• - - Private Members in Extensions
• - Generics
• - Type Aliases

Access Control

Modules and Source Files

Access Levels

Guiding Principle of Access Levels

Default Access Levels

Access Levels for Single-Target Apps

Access Levels for Frameworks

Access Levels for Unit Test Targets

Access Control Syntax

public class SomePublicClass {}
internal class SomeInternalClass {}
fileprivate class SomeFilePrivateClass {}
private class SomePrivateClass {}

public var somePublicVariable = 0
internal let someInternalConstant = 0
fileprivate func someFilePrivateFunction() {}
private func somePrivateFunction() {}

class SomeInternalClass {}              // implicitly internal
let someInternalConstant = 0            // implicitly internal

Custom Types

public class SomePublicClass {                  // explicitly public class
    public var somePublicProperty = 0            // explicitly public class member
    var someInternalProperty = 0                 // implicitly internal class member
    fileprivate func someFilePrivateMethod() {}  // explicitly file-private class member
    private func somePrivateMethod() {}          // explicitly private class member
}

class SomeInternalClass {                       // implicitly internal class
    var someInternalProperty = 0                 // implicitly internal class member
    fileprivate func someFilePrivateMethod() {}  // explicitly file-private class member
    private func somePrivateMethod() {}          // explicitly private class member
}

fileprivate class SomeFilePrivateClass {        // explicitly file-private class
    func someFilePrivateMethod() {}              // implicitly file-private class member
    private func somePrivateMethod() {}          // explicitly private class member
}

private class SomePrivateClass {                // explicitly private class
    func somePrivateMethod() {}                  // implicitly private class member
}

Tuple Types

Function Types

func someFunction() -> (SomeInternalClass, SomePrivateClass) {
    // function implementation goes here
}

private func someFunction() -> (SomeInternalClass, SomePrivateClass) {
    // function implementation goes here
}

Enumeration Types

public enum CompassPoint {
    case north
    case south
    case east
    case west
}

Nested Types

Subclassing

public class A {
    fileprivate func someMethod() {}
}

internal class B: A {
    override internal func someMethod() {}
}

public class A {
    fileprivate func someMethod() {}
}

internal class B: A {
    override internal func someMethod() {
        super.someMethod()
    }
}

Constants, Variables, Properties, and Subscripts

private var privateInstance = SomePrivateClass()

Getters and Setters

struct TrackedString {
    private(set) var numberOfEdits = 0
    var value: String = "" {
        didSet {
            numberOfEdits += 1
        }
    }
}

var stringToEdit = TrackedString()
stringToEdit.value = "This string will be tracked."
stringToEdit.value += " This edit will increment numberOfEdits."
stringToEdit.value += " So will this one."
print("The number of edits is \(stringToEdit.numberOfEdits)")
// Prints "The number of edits is 3"

public struct TrackedString {
    public private(set) var numberOfEdits = 0
    public var value: String = "" {
        didSet {
            numberOfEdits += 1
        }
    }
    public init() {}
}

Initializers

Default Initializers

Default Memberwise Initializers for Structure Types

Protocols

Protocol Inheritance

Protocol Conformance

Extensions

Private Members in Extensions

protocol SomeProtocol {
    func doSomething()
}

struct SomeStruct {
    private var privateVariable = 12
}

extension SomeStruct: SomeProtocol {
    func doSomething() {
        print(privateVariable)
    }
}

Generics

Type Aliases