参考了:https://casatwy.com/responder_chain_communication.html
参考了:https://github.com/qingfengiOS/MutableCellTableView
一般对象之间事件监听我们可以用代理,比如这种情况,控制器的子view(CustomView),上有一个btn点击事件,一般这种事件监听应该交由控制器统一处理
@protocol CustomViewDelegate <NSObject>
- (void)btnClick:(UIButton *)btn;
@end
@interface CustomView : UIView
@property (nonatomic, weak) id<CustomViewDelegate> delegate;
@end
- (IBAction)btnClick:(UIButton *)sender {
if ([_delegate respondsToSelector:@selector(btnClick:)]) {
[_delegate btnClick:sender];
}
}
在控制器中遵守协议,控制器作为代理,然后实现代理方法
// 在控制器中遵守协议
@interface ViewController ()<CustomViewDelegate>
@end
- (void)viewDidLoad {
[super viewDidLoad];
CustomView *customV = [[NSBundle mainBundle] loadNibNamed:@"CustomView" owner:self options:nil].firstObject;
customV.frame = CGRectMake(10, 100, [UIScreen mainScreen].bounds.size.width-10, 250);
[self.view addSubview:customV];
// 控制器作为代理
customV.delegate = self;
}
// 实现代理方法
- (void)btnClick:(nonnull UIButton *)btn {
NSLog(@"%s,parameter=%@",__func__,btn);
}
然而,发现一个新的思路:使用UIResponder实现事件响应链条传递事件,凡是继承UIResponder的控件都可以比如UIView,我们知道大部分控件都是直接或者间接继承自UIView,比如UIButton,UILabel,UIImageView,UIControl,UISwitch,UIScrollView,UITextView,UITextField,UISearchBar,UIPickerView等等
1.给UIResponder扩展分类
@interface UIResponder (Router)
/**
凡是继承UIResponder的控件,都可以通过事件响应链条传递事件
@param eventName 事件名
@param userInfo 附加参数,nullable可以为空
*/
- (void)routerEventWithName:(NSString *)eventName userInfo:(nullable NSDictionary *)userInfo;
/**
通过方法SEL生成NSInvocation
@param selector 方法
@return Invocation对象
*/
- (NSInvocation *)createInvocationWithSelector:(SEL)selector;
@end
实现
@implementation UIResponder (Router)
- (void)routerEventWithName:(NSString *)eventName userInfo:(nullable NSDictionary *)userInfo{
NSLog(@"UIResponder---eventName=%@,userInfo=%@",eventName,userInfo);
[[self nextResponder] routerEventWithName:eventName userInfo:userInfo];
}
- (NSInvocation *)createInvocationWithSelector:(SEL)selector{
// 通过方法名创建方法签名 注意:不能使用 [[NSInvocation alloc] init]也不可以用下面这个方法
// NSMethodSignature *signature = [NSInvocation instanceMethodSignatureForSelector:selector];
NSMethodSignature *signature = [[self class] instanceMethodSignatureForSelector:selector];
// 通过方法签名创建invocation
// signature == nil 这里就会崩溃
NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:signature];
[invocation setTarget:self];
[invocation setSelector:selector];
return invocation;
}
2.发送事件(子view中)
#import "UIResponder+Router.h"
- (IBAction)btnClick:(UIButton *)sender {
[self routerEventWithName:kEventMyButtonName userInfo: @{@"btnKey": sender.currentTitle}];
}
3.响应处理事件(以控制器为示例)
#import "UIResponder+Router.h"
#pragma mark - Event Response
- (void)routerEventWithName:(NSString *)eventName userInfo:(NSDictionary *)userInfo{
NSLog(@"controller---eventName=%@,userInfo=%@",eventName,userInfo);
// 处理事件
[self handleEventWithName:eventName parameter:userInfo];
// 如果有需求 可以把响应链继续传递下去 和super 一样效果
[[self nextResponder] routerEventWithName:eventName userInfo:userInfo];
// [super routerEventWithName:eventName userInfo:userInfo];
}
// 处理事件
- (void)handleEventWithName:(NSString *)eventName parameter:(NSDictionary *)parameter{
// 获取invocation对象
NSInvocation *invocation = self.eventStrategyDictionary[eventName];
// 设置invocation参数
// 因为有两个隐藏参数self和_cmd,所有index从2开始
[invocation setArgument:¶meter atIndex:2];
// 调用方法
[invocation invoke];
}
Strategy模式进行更好的事件处理
/// 事件策略字典 key:事件名 value:事件的invocation对象
@property (strong, nonatomic) NSDictionary *eventStrategyDictionary;
#pragma mark - Getter
- (NSDictionary <NSString *, NSInvocation *>*)eventStrategyDictionary {
if (!_eventStrategyDictionary) {
NSInvocation *btnInvocation = [self createInvocationWithSelector:@selector(customViewButtonClickWithParameter:)];
NSInvocation *switchInvocation = [self createInvocationWithSelector:@selector(customViewSwitchValueChangeWithParameter:)];
NSInvocation *imgInvocation = [self createInvocationWithSelector:@selector(customViewImageViewTapWithParameter:)];
_eventStrategyDictionary = @{ kEventMyButtonName: btnInvocation,
kEventMySwitchName: switchInvocation,
kEventMyImageViewName: imgInvocation
};
}
return _eventStrategyDictionary;
}
// 处理button点击事件
- (void)customViewButtonClickWithParameter:(NSDictionary *)parameter{
NSLog(@"%s,parameter=%@",__func__,parameter);
}
使用Strategy模式，即可避免多事件处理场景下导致的冗长if-else语句
对响应链的调用打印
UIResponder---eventName=CustomSwitchEvent,userInfo={
mySwitchKey = 0;
}
UIResponder---eventName=CustomSwitchEvent,userInfo={
mySwitchKey = 0;
}
controller---eventName=CustomSwitchEvent,userInfo={
mySwitchKey = 0;
}
[ViewController customViewSwitchValueChangeWithParameter:],parameter={
mySwitchKey = 0;
}
UIResponder---eventName=CustomSwitchEvent,userInfo={
mySwitchKey = 0;
}
UIResponder---eventName=CustomSwitchEvent,userInfo={
mySwitchKey = 0;
}
AppDelegate---eventName=CustomSwitchEvent,userInfo={
mySwitchKey = 0;
}
由于响应链是一层一层往上传递的,最终会经过AppDelegate,所以如果要对所有事件做统一处理可以在AppDelegate这里
#import "UIResponder+Router.h"
@interface AppDelegate ()
@end
@implementation AppDelegate
- (void)routerEventWithName:(NSString *)eventName userInfo:(NSDictionary *)userInfo{
NSLog(@"AppDelegate---eventName=%@,userInfo=%@",eventName,userInfo);
}
@end
在整个响应链中,任何响应的地方都可以处理,比如添加一些参数(可使用Decorator模式，能够更加有序地收集、归拢数据，降低了工程的维护成本),处理一些业务逻辑
如果页面比较复杂,比如商品详情页,业务逻辑非常多,我们可以新建一个文件(EventProxy),把所有的响应事件放到这个文件进行统一处理,这样就达到了为控制器减负,看起来有点像新的架构
新的架构模式：MVCE（Modle View Controller Event)
EventProxy.h的声明
@interface EventProxy : NSObject
- (void)handleEventWithName:(NSString *)eventName parameter:(NSDictionary *)parameter;
@end
EventProxy.m的实现
#import "EventProxy.h"
#import "UIResponder+Router.h"
NSString *const kEventMyButtonName = @"CustomButtonEvent";
NSString *const kEventMySwitchName = @"CustomSwitchEvent";
NSString *const kEventMyImageViewName = @"CustomImageViewEvent";
@interface EventProxy ()
// 使用Strategy模式，即可避免多事件处理场景下导致的冗长if-else语句
/// 事件策略字典 key:事件名 value:事件的invocation对象
@property (strong, nonatomic) NSDictionary *eventStrategyDictionary;
@end
@implementation EventProxy
- (NSInvocation *)createInvocationWithSelector:(SEL)selector{
// 通过方法名创建方法签名 注意:不能使用 [[NSInvocation alloc] init]也不可以用下面这个方法
// NSMethodSignature *signature = [NSInvocation instanceMethodSignatureForSelector:selector];
NSMethodSignature *signature = [[self class] instanceMethodSignatureForSelector:selector];
// 通过方法签名创建invocation
// signature == nil 这里就会崩溃
NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:signature];
[invocation setTarget:self];
[invocation setSelector:selector];
return invocation;
}
#pragma mark - Getter
- (NSDictionary <NSString *, NSInvocation *>*)eventStrategyDictionary {
if (!_eventStrategyDictionary) {
NSInvocation *btnInvocation = [self createInvocationWithSelector:@selector(customViewButtonClickWithParameter:)];
NSInvocation *switchInvocation = [self createInvocationWithSelector:@selector(customViewSwitchValueChangeWithParameter:)];
NSInvocation *imgInvocation = [self createInvocationWithSelector:@selector(customViewImageViewTapWithParameter:)];
_eventStrategyDictionary = @{ kEventMyButtonName: btnInvocation,
kEventMySwitchName: switchInvocation,
kEventMyImageViewName: imgInvocation
};
}
return _eventStrategyDictionary;
}
- (void)handleEventWithName:(NSString *)eventName parameter:(NSDictionary *)parameter{
// 获取invocation对象
NSInvocation *invocation = self.eventStrategyDictionary[eventName];
// 设置invocation参数
// 因为有两个隐藏参数self和_cmd,所有index从2开始
[invocation setArgument:¶meter atIndex:2];
// 调用方法
[invocation invoke];
}
- (void)customViewButtonClickWithParameter:(NSDictionary *)parameter{
NSLog(@"具体方法实现,parameter=%@",parameter);
}
- (void)customViewSwitchValueChangeWithParameter:(NSDictionary *)parameter{
NSLog(@"具体方法实现,parameter=%@",parameter);
}
- (void)customViewImageViewTapWithParameter:(NSDictionary *)parameter{
NSLog(@"具体方法实现,parameter=%@",parameter);
}
控制器中的代码实现
@interface ViewController ()
@property (strong, nonatomic) EventProxy *eventProxy;
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
// 初始化事件代理
self.eventProxy = [[EventProxy alloc] init];
}
#pragma mark - Event Response
- (void)routerEventWithName:(NSString *)eventName userInfo:(NSDictionary *)userInfo{
NSLog(@"controller---eventName=%@,userInfo=%@",eventName,userInfo);
// 处理事件
[self.eventProxy handleEventWithName:eventName parameter:userInfo];
// 把响应链继续传递下去 和super 一样效果
[[self nextResponder] routerEventWithName:eventName userInfo:userInfo];
// [super routerEventWithName:eventName userInfo:userInfo];
}
@end
这样控制器把事件的处理交给eventProxy去处理,这样控制器是不是很清爽呢,是不是很像MVCE（Modle View Controller Event)
总结一下:
- 1.在子view中发送事件
- 2.一般在控制器中处理事件,也可以发送给一个专门对象
eventProxy进行处理这个事件 - 3.如果有需要可以继续传给其他地方进行处理,比如父控件,
AppDelegate
