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January 22, 2023 20:28
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UIApplication Swift category to add visibleViewControllers property
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import UIKit | |
extension UIApplication { | |
private struct AssociatedObjectsKeys { | |
static var visibleViewControllersPointers = "UIApplication_visibleViewControllersPointers" | |
} | |
fileprivate var visibleViewControllersPointers: NSPointerArray { | |
var pointers = objc_getAssociatedObject(self, &AssociatedObjectsKeys.visibleViewControllersPointers) as! NSPointerArray? | |
if (pointers == nil) { | |
pointers = NSPointerArray.weakObjects() | |
objc_setAssociatedObject(self, &AssociatedObjectsKeys.visibleViewControllersPointers, pointers, objc_AssociationPolicy.OBJC_ASSOCIATION_RETAIN_NONATOMIC) | |
} | |
return pointers! | |
} | |
var visibleViewControllers: [UIViewController] { | |
return visibleViewControllersPointers.allObjects as! [UIViewController] | |
} | |
} | |
extension UIViewController { | |
private static func swizzleFunc(withOriginalSelector originalSelector: Selector, swizzledSelector: Selector) { | |
let originalMethod = class_getInstanceMethod(self, originalSelector) | |
let swizzledMethod = class_getInstanceMethod(self, swizzledSelector) | |
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); | |
} | |
} | |
override open class func initialize() { | |
if self != UIViewController.self { | |
return | |
} | |
let swizzlingClosure: () = { | |
UIViewController.swizzleFunc(withOriginalSelector: #selector(UIViewController.viewDidAppear(_:)), | |
swizzledSelector: #selector(uiapplication_visibleviewcontrollers_viewDidAppear(_:))) | |
UIViewController.swizzleFunc(withOriginalSelector: #selector(UIViewController.viewDidDisappear(_:)), | |
swizzledSelector: #selector(uiapplication_visibleviewcontrollers_viewDidDisappear(_:))) | |
}() | |
swizzlingClosure | |
} | |
@objc private func uiapplication_visibleviewcontrollers_viewDidAppear(_ animated: Bool) { | |
UIApplication.shared.visibleViewControllersPointers.addPointer(Unmanaged.passUnretained(self).toOpaque()) | |
uiapplication_visibleviewcontrollers_viewDidAppear(animated) | |
} | |
@objc private func uiapplication_visibleviewcontrollers_viewDidDisappear(_ animated: Bool) { | |
let pointers = UIApplication.shared.visibleViewControllersPointers | |
for i in 0..<pointers.count { | |
if let pointer = pointers.pointer(at: i) { | |
let viewController = Unmanaged<UIViewController>.fromOpaque(pointer).takeUnretainedValue() | |
if viewController.isEqual(self) { | |
pointers.removePointer(at: i) | |
break | |
} | |
} | |
} | |
uiapplication_visibleviewcontrollers_viewDidDisappear(animated) | |
} | |
} |
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