iOS 使用消息转发机制实现多代理功能

在iOS开发中，我们有时候会用到多代理功能，比如我们列表的埋点事件，需要我们在列表的某个特定的时机进行埋点上报，我们当然可以用最常见的做法，就是设置代理实现代理方法，然后在对应的代理方法里面进行上报，但是这样做有个问题，就是会做大量重复的工作，我们想要到达的效果是，我们只需要实现业务逻辑，而埋点操作，只需需要我们配置一下数据，就会自动进行，这样就为我们减少了大量的重复性工作。
下面介绍一下我们实现列表的自定化埋点的思路
我们自定义一个列表类，继承于系统类，然后该类有一个代理中心，
该代理中心类负责消息转发，他引用了真正的原始代理，和一个代理对象，该代理对象也实现了列表的代理方法，里面的实现只进行埋点操作。 我们重写自定义列表类的setDelegate方法，在里面创建代理对象，并将列表的代理设置为代理中心，在代理中心中将消息转发给代理对象和原始代理， 通过这样的方式，实现了自动化埋点
代码
代理中心

//
//  LBDelegateCenter.m
//  TEXT
//
//  Created by mac on 2025/3/2.
//  Copyright © 2025 刘博. All rights reserved.
//#import "LBDelegateCenter.h"@implementation LBDelegateCenter- (instancetype)initWithTarget:(id)target proxy:(id)proxy
{if (self = [super init]) {_target = target ? target : [NSNull null];_proxy = proxy ? proxy : [NSNull null];}return self;
}- (NSMethodSignature *)methodSignatureForSelector:(SEL)sel
{NSMethodSignature *targetSign = [_target methodSignatureForSelector:sel];if (targetSign) {return targetSign;}NSMethodSignature *proxySign = [_proxy methodSignatureForSelector:sel];if (proxySign) {return proxySign;}return [super methodSignatureForSelector:sel];
}- (void)forwardInvocation:(NSInvocation *)anInvocation
{//AUKLogInfo(@"New proxy = %@, selector=%@", [self.proxy class], NSStringFromSelector([anInvocation selector]));BOOL hit = NO;if ([_target respondsToSelector:[anInvocation selector]]) {hit = YES;[anInvocation invokeWithTarget:_target];}if ([_proxy respondsToSelector:[anInvocation selector]]) {//AUKLogInfo(@"New proxy handle");hit = YES;[anInvocation invokeWithTarget:_proxy];}if (!hit && [super respondsToSelector:[anInvocation selector]]) {[super forwardInvocation:anInvocation];}
}- (BOOL)respondsToSelector:(SEL)aSelector
{if ([_target respondsToSelector:aSelector]) {return YES;}if ([_proxy respondsToSelector:aSelector]) {return YES;}return [super respondsToSelector:aSelector];
}- (BOOL)conformsToProtocol:(Protocol *)aProtocol
{if ([_target conformsToProtocol:aProtocol]) {return YES;}if ([_proxy conformsToProtocol:aProtocol]) {return YES;}return [super conformsToProtocol:aProtocol];
}- (BOOL)isKindOfClass:(Class)aClass
{if ([_target isKindOfClass:aClass]) {return YES;}if ([_proxy isKindOfClass:aClass]) {return YES;}return [super isKindOfClass:aClass];
}- (BOOL)isMemberOfClass:(Class)aClass
{if ([_target isMemberOfClass:aClass]) {return YES;}if ([_proxy isMemberOfClass:aClass]) {return YES;}return [super isMemberOfClass:aClass];
}@end

代理对象

//
//  LBScrollViewDelegate.m
//  TEXT
//
//  Created by mac on 2025/3/2.
//  Copyright © 2025 刘博. All rights reserved.
//#import "LBScrollViewDelegate.h"
#import <UIKit/UIKit.h>
#import "UITableViewCell+Event.h"
#import "UICollectionViewCell+Event.h"@implementation LBScrollViewDelegate// 自动轮播的开始，但是需要重点关注是否可能存在触发scrollViewDidScroll
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{//执行滚动
}- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView
{//开始拖动，执行曝光埋点
}//
- (void)scrollViewWillBeginDecelerating:(UIScrollView *)scrollView
{//开始减速， 停止滚动
}//
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{//停止减速
}//
- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate
{if (!decelerate) {//停止滚动}
}//
- (void)scrollViewDidEndScrollingAnimation:(UIScrollView *)scrollView
{//
}// 10.3.86 切换使用新方法代替点击捕获
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];[cell setMonitorSelected:YES];
}- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{UICollectionViewCell *cell = [collectionView cellForItemAtIndexPath:indexPath];[cell setMonitorSelected:YES];
}// 结束显示周期是准确的，但开始显示可能只显示一次，可能显示并不完全，所以暂只开了开始。
- (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath
{if ([self needCheckCellIn:tableView isStart:YES]) {}
}- (void)collectionView:(UICollectionView *)collectionView willDisplayCell:(UICollectionViewCell *)cell forItemAtIndexPath:(NSIndexPath *)indexPath
{if ([self needCheckCellIn:collectionView isStart:YES]) {}
}- (void)tableView:(UITableView *)tableView didEndDisplayingCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath*)indexPath
{if ([self needCheckCellIn:tableView isStart:NO]) {}
}- (void)collectionView:(UICollectionView *)collectionView didEndDisplayingCell:(UICollectionViewCell *)cell forItemAtIndexPath:(NSIndexPath *)indexPath
{if ([self needCheckCellIn:collectionView isStart:NO]) {}
}- (BOOL)needCheckCellIn:(UIView *)view isStart:(BOOL)start
{return YES;
}@end

自定义列表类

//
//  LBCollectionView.m
//  TEXT
//
//  Created by mac on 2025/3/2.
//  Copyright © 2025 刘博. All rights reserved.
//#import "LBEventCollectionView.h"
#import "LBScrollViewDelegate.h"
#import "LBDelegateCenter.h"@implementation LBEventCollectionView- (void)didMoveToWindow
{[super didMoveToWindow];//执行cell 曝光埋点
}- (void)reloadData
{[super reloadData];[self checkNeedReportLog_auk];}- (void)checkNeedReportLog_auk
{if (!self.window || !self.superview) {return;}// 上报当前visiblecell及其子view的所有埋点，放到下一个runloop,等到cell渲染完成[NSObject cancelPreviousPerformRequestsWithTarget:self selector:@selector(performCommitScroll) object:nil];[self performSelector:@selector(performCommitScroll) withObject:nil afterDelay:0.5];}- (void)performCommitScroll
{//执行曝光埋点
}- (LBScrollViewDelegate *)collectionDelegate_auk
{if (!_collectionDelegate_auk) {_collectionDelegate_auk = [[LBScrollViewDelegate alloc] init];}return _collectionDelegate_auk;
}- (void)setDelegate:(id<UICollectionViewDelegate>)delegate
{if (delegate == nil) {
//        self.delegateProxy_auk = nil;[super setDelegate:nil];return;}self.delegateProxy_auk = [[LBDelegateCenter alloc] initWithTarget:self.collectionDelegate_auk proxy:delegate];self.delegateProxy_auk.scrollView = self;[super setDelegate:(id)self.delegateProxy_auk];
}- (NSMutableDictionary *)visibleCellInfos_auk
{if (!_visibleCellInfos_auk) {_visibleCellInfos_auk = [[NSMutableDictionary alloc] init];}return _visibleCellInfos_auk;
}- (NSMutableDictionary *)lastVisibleInfos_auk
{if (!_lastVisibleInfos_auk) {_lastVisibleInfos_auk = [[NSMutableDictionary alloc] init];}return _lastVisibleInfos_auk;
}- (NSHashTable *)validViews_auk
{if (!_validViews_auk) {_validViews_auk = [NSHashTable hashTableWithOptions:NSHashTableWeakMemory];}return _validViews_auk;
}- (void)dealloc
{
//    self.delegate = nil;_delegateProxy_auk = nil;_collectionDelegate_auk = nil;
}- (BOOL)supportAspectExposure
{return NO;
}@end