मैं के लिए एक श्रेणी बनाई UIApplicationके साथ visibleViewControllersसंपत्ति। मुख्य विचार बहुत सरल है। मैं झेंप गया viewDidAppearऔर viewDidDisappearतरीकों में UIViewController। में viewDidAppearविधि ViewController ढेर में जोड़ा जाता है। में viewDidDisappearविधि ViewController ढेर से निकाल दिया जाता। कमजोर संदर्भों को संग्रहीत करने के NSPointerArrayबजाय उपयोग किया जाता है । यह दृष्टिकोण किसी भी दृश्य नियंत्रक के लिए काम करता है।NSArrayUIViewController
UIApplication + VisibleViewControllers.h
#import <UIKit/UIKit.h>
@interface UIApplication (VisibleViewControllers)
@property (nonatomic, readonly) NSArray<__kindof UIViewController *> *visibleViewControllers;
@end
UIApplication + VisibleViewControllers.m
#import "UIApplication+VisibleViewControllers.h"
#import <objc/runtime.h>
@interface UIApplication ()
@property (nonatomic, readonly) NSPointerArray *visibleViewControllersPointers;
@end
@implementation UIApplication (VisibleViewControllers)
- (NSArray<__kindof UIViewController *> *)visibleViewControllers {
return self.visibleViewControllersPointers.allObjects;
}
- (NSPointerArray *)visibleViewControllersPointers {
NSPointerArray *pointers = objc_getAssociatedObject(self, @selector(visibleViewControllersPointers));
if (!pointers) {
pointers = [NSPointerArray weakObjectsPointerArray];
objc_setAssociatedObject(self, @selector(visibleViewControllersPointers), pointers, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
return pointers;
}
@end
@implementation UIViewController (UIApplication_VisibleViewControllers)
+ (void)swizzleMethodWithOriginalSelector:(SEL)originalSelector swizzledSelector:(SEL)swizzledSelector {
Method originalMethod = class_getInstanceMethod(self, originalSelector);
Method swizzledMethod = class_getInstanceMethod(self, swizzledSelector);
BOOL 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);
}
}
+ (void)load {
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
[self swizzleMethodWithOriginalSelector:@selector(viewDidAppear:)
swizzledSelector:@selector(uiapplication_visibleviewcontrollers_viewDidAppear:)];
[self swizzleMethodWithOriginalSelector:@selector(viewDidDisappear:)
swizzledSelector:@selector(uiapplication_visibleviewcontrollers_viewDidDisappear:)];
});
}
- (void)uiapplication_visibleviewcontrollers_viewDidAppear:(BOOL)animated {
[[UIApplication sharedApplication].visibleViewControllersPointers addPointer:(__bridge void * _Nullable)self];
[self uiapplication_visibleviewcontrollers_viewDidAppear:animated];
}
- (void)uiapplication_visibleviewcontrollers_viewDidDisappear:(BOOL)animated {
NSPointerArray *pointers = [UIApplication sharedApplication].visibleViewControllersPointers;
for (int i = 0; i < pointers.count; i++) {
UIViewController *viewController = [pointers pointerAtIndex:i];
if ([viewController isEqual:self]) {
[pointers removePointerAtIndex:i];
break;
}
}
[self uiapplication_visibleviewcontrollers_viewDidDisappear:animated];
}
@end
https://gist.github.com/medvedzzz/e6287b99011f2437ac0beb5a72a897f0
स्विफ्ट 3 संस्करण
UIApplication + VisibleViewControllers.swift
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<AnyObject>.fromOpaque(pointer).takeUnretainedValue() as? UIViewController
if viewController.isEqual(self) {
pointers.removePointer(at: i)
break
}
}
}
uiapplication_visibleviewcontrollers_viewDidDisappear(animated)
}
}
https://gist.github.com/medvedzzz/ee6f4071639d987793977dba04e11399