ios - ¿Cómo implementar el método swizzling swift 3.0?

xcode swift3

Question

¿Cómo puedo implementar el método swizzling en Swift 3.0 ?

He leído el artículo de nshipster al respecto, pero en el fragmento de este código

struct Static {
    static var token: dispatch_once_t = 0
}

el compilador me da un error

dispatch_once_t no está disponible en Swift: en su lugar, use globales globalizados perezosamente

Answer 1

@TikhonovAlexander: Gran respuesta

Modifiqué el swizzler para tomar ambos selectores y lo hice más genérico.

Swift 3

private let swizzling: (AnyClass, Selector, Selector) -> () = { forClass, originalSelector, swizzledSelector in
    let originalMethod = class_getInstanceMethod(forClass, originalSelector)
    let swizzledMethod = class_getInstanceMethod(forClass, swizzledSelector)
    method_exchangeImplementations(originalMethod, swizzledMethod)
}

// perform swizzling in initialize()

extension UIView {

    open override class func initialize() {
        // make sure this isn''t a subclass
        guard self === UIView.self else { return }

        let originalSelector = #selector(layoutSubviews)
        let swizzledSelector = #selector(swizzled_layoutSubviews)
        swizzling(self, originalSelector, swizzledSelector)
    }

    func swizzled_layoutSubviews() {
        swizzled_layoutSubviews()
        print("swizzled_layoutSubviews")
    }

}

Swift 4

private let swizzling: (AnyClass, Selector, Selector) -> () = { forClass, originalSelector, swizzledSelector in
    guard
        let originalMethod = class_getInstanceMethod(forClass, originalSelector),
        let swizzledMethod = class_getInstanceMethod(forClass, swizzledSelector)
    else { return }
    method_exchangeImplementations(originalMethod, swizzledMethod)
}

extension UIView {

    static let classInit: Void = {            
        let originalSelector = #selector(layoutSubviews)
        let swizzledSelector = #selector(swizzled_layoutSubviews)
        swizzling(UIView.self, originalSelector, swizzledSelector)
    }()

    @objc func swizzled_layoutSubviews() {
        swizzled_layoutSubviews()
        print("swizzled_layoutSubviews")
    }

}

// perform swizzling in AppDelegate.init()

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    override init() {
        super.init()
        UIView.classInit
    }

}

Answer 2

En primer lugar, dispatch_once_t no está disponible en Swift 3.0. Puedes elegir entre dos alternativas:

1. Variable global

2. Propiedad estática de struct , enum o class

Para más detalles, vea que Whither dispatch_once en Swift 3

Para diferentes propósitos debes usar diferentes implementaciones de swizzling

• Clase Swizzling CocoaTouch, por ejemplo UIViewController;
• Swift clase Swift personalizada;

Clase Swatching CocoaTouch

ejemplo swizzling viewWillAppear(_:) de UIViewController usando variable global

private let swizzling: (UIViewController.Type) -> () = { viewController in

    let originalSelector = #selector(viewController.viewWillAppear(_:))
    let swizzledSelector = #selector(viewController.proj_viewWillAppear(animated:))

    let originalMethod = class_getInstanceMethod(viewController, originalSelector)
    let swizzledMethod = class_getInstanceMethod(viewController, swizzledSelector)

    method_exchangeImplementations(originalMethod, swizzledMethod) }

extension UIViewController {

    open override class func initialize() {
        // make sure this isn''t a subclass
        guard self === UIViewController.self else { return }
        swizzling(self)
    }

    // MARK: - Method Swizzling

    func proj_viewWillAppear(animated: Bool) {
        self.proj_viewWillAppear(animated: animated)

        let viewControllerName = NSStringFromClass(type(of: self))
        print("viewWillAppear: /(viewControllerName)")
    } 
 }

Clase Swift personalizada Swizzling

Para utilizar el método swizzling con sus clases Swift, debe cumplir dos requisitos ( para obtener más detalles ):

• La clase que contiene los métodos que se deben mezclar debe extender NSObject
• Los métodos que desea mezclar deben tener el atributo dynamic

Y ejemplo, método swizzling de la clase base personalizada Swift Person

class Person: NSObject {
    var name = "Person"
    dynamic func foo(_ bar: Bool) {
        print("Person.foo")
    }
}

class Programmer: Person {
    override func foo(_ bar: Bool) {
        super.foo(bar)
        print("Programmer.foo")
    }
}

private let swizzling: (Person.Type) -> () = { person in

    let originalSelector = #selector(person.foo(_:))
    let swizzledSelector = #selector(person.proj_foo(_:))

    let originalMethod = class_getInstanceMethod(person, originalSelector)
    let swizzledMethod = class_getInstanceMethod(person, swizzledSelector)

    method_exchangeImplementations(originalMethod, swizzledMethod)
}

extension Person {

    open override class func initialize() {
        // make sure this isn''t a subclass
        guard self === Person.self else { return }
        swizzling(self)
    }

    // MARK: - Method Swizzling

    func proj_foo(_ bar: Bool) {
        self.proj_foo(bar)

        let className = NSStringFromClass(type(of: self))
        print("class: /(className)")
    }
}

Answer 3

chapoteando en el patio de recreo
Swift 4.2

import Foundation
class TestSwizzling : NSObject {
    @objc dynamic func methodOne()->Int{
        return 1
    }
}

extension TestSwizzling {

    //In Objective-C you''d perform the swizzling in load(),
    //but this method is not permitted in Swift
    func swizzle(){

        let i: () -> () = {

            let originalSelector = #selector(TestSwizzling.methodOne)
            let swizzledSelector = #selector(TestSwizzling.methodTwo)
            let originalMethod = class_getInstanceMethod(TestSwizzling.self, originalSelector);
            let swizzledMethod = class_getInstanceMethod(TestSwizzling.self, swizzledSelector)
            method_exchangeImplementations(originalMethod!, swizzledMethod!)
            print("swizzled")

        }
        i()
    }

    @objc func methodTwo()->Int{
        // It will not be a recursive call anymore after the swizzling
        return 4
    }
}

var c = TestSwizzling()
print([c.methodOne(),c.methodTwo()])
c.swizzle()
print([c.methodOne(),c.methodTwo()])

salida:
[1, 4]
swizzled
[4, 1]