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November 23, 2017 09:10
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Swizzling
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| // AppDelegate | |
| func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool { | |
| UIViewController.doSwizzleStuff() | |
| } | |
| // extension | |
| // MARK: - Swizzling | |
| private var hasSwizzled = false | |
| extension UIViewController { | |
| final public class func doSwizzleStuff() { | |
| guard !hasSwizzled else { return } | |
| hasSwizzled = true | |
| // make sure this isn't a subclass | |
| if self !== UIViewController.self { | |
| return | |
| } | |
| let originalSelector = #selector(viewDidLoad) | |
| let swizzledSelector = #selector(my_viewDidLoad) | |
| let originalMethod = class_getInstanceMethod(self, originalSelector) | |
| let swizzledMethod = class_getInstanceMethod(self, swizzledSelector) | |
| guard originalMethod != nil, swizzledMethod != nil else { | |
| return | |
| } | |
| let didAddMethod = class_addMethod(self, originalSelector, method_getImplementation(swizzledMethod!), method_getTypeEncoding(swizzledMethod!)) | |
| if didAddMethod { | |
| class_replaceMethod(self, swizzledSelector, method_getImplementation(originalMethod!), method_getTypeEncoding(originalMethod!)) | |
| } else { | |
| method_exchangeImplementations(originalMethod!, swizzledMethod!) | |
| } | |
| } | |
| // MARK: - Method Swizzling | |
| @objc func my_viewDidLoad() { | |
| self.my_viewDidLoad() | |
| } | |
| } |
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