ฉันสร้างหมวดหมู่สำหรับUIApplicationด้วยvisibleViewControllersคุณสมบัติ แนวคิดหลักนั้นค่อนข้างเรียบง่าย ฉันหมุนviewDidAppearและviewDidDisappearวิธีการในUIViewController. ในviewDidAppearเมธอด viewController ถูกเพิ่มลงใน stack ในviewDidDisappearเมธอด viewController จะถูกลบออกจากสแต็ก NSPointerArrayใช้แทนNSArrayการเก็บจุดอ่อนUIViewControllerข้อมูลอ้างอิงที่แนวทางนี้ใช้ได้กับลำดับชั้นของ viewControllers
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
เวอร์ชัน Swift 3
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