RAC 响应式编程

1、特点：
在事件发生的时候立刻做出反应。

2、以下操作都是响应式编程：
Target
Delegate
KVO
通知
时钟
网络异步回调

3、目的：
接管事件的监听

4、注意（坑）：
（1）RAC最大的坑是循环引用
（2）多人开发中，确保所有人的代码风格一致
（3）个人开发，要注意版本对应的语言：
2.5以下全都是OC，
3.0是OC末代，
4.0开始swift2.0
5.0开始支持swift3.0
6.0开始支持swift4.1 等等，
具体看github的介绍吧。

初识

    //RACSignal 信号    /*     创建信号     订阅信号     发送信号     */    //创建    RACSignal *sigal = [RACSignal createSignal:^RACDisposable * _Nullable(id<RACSubscriber>  _Nonnull subscriber) {        NSLog(@"创建了信号");        //发送        [subscriber sendNext:@"this is RAC"];        NSLog(@"发送了信号");        return nil;    }];    //订阅    [sigal subscribeNext:^(id  _Nullable x) {        //x 信号的内容        NSLog(@"%@",x);        NSLog(@"订阅了信号");    }];    /*     2017-10-10 15:14:25.875726+0800 RAC[23884:952541] 创建了信号     2017-10-10 15:14:25.875982+0800 RAC[23884:952541] this is RAC     2017-10-10 15:14:25.876127+0800 RAC[23884:952541] 订阅了信号     2017-10-10 15:14:25.876640+0800 RAC[23884:952541] 发送了信号     */    /*     创建信号必须先订阅     订阅信号必须先发送     */

KVO

   [RACObserve(self.person, name) subscribeNext:^(id  _Nullable x) {        NSLog(@"%@",x);    }];

Target

    [[self.btn rac_signalForControlEvents:UIControlEventTouchUpInside] subscribeNext:^(__kindof UIControl * _Nullable x) {        // x is btn        NSLog(@"%@",x);    }];

Delegate

    [[self.field rac_textSignal] subscribeNext:^(NSString * _Nullable x) {        NSLog(@"%@",x);    }];

通知

    [[[NSNotificationCenter defaultCenter] rac_addObserverForName:@"qwe" object:nil] subscribeNext:^(NSNotification * _Nullable x) {        NSLog(@"%@",x);    }];

组合 (登录为例)

    //x is 0 or 1    // so    RAC(self.btn,enabled) =    [[RACSignal combineLatest:@[self.field.rac_textSignal,self.field2.rac_textSignal]] reduceEach:^id _Nullable(NSString *account ,NSString *pwd){        return @(account.length && account.length);    }];    //命令    RACCommand *command = [[RACCommand alloc] initWithSignalBlock:^RACSignal * _Nonnull(id  _Nullable input) {        NSLog(@"密码加密");        return [RACSignal createSignal:^RACDisposable * _Nullable(id<RACSubscriber>  _Nonnull subscriber) {            [subscriber sendNext:@"请求登录"];            [subscriber sendCompleted]; //发出命令完成            return nil;        }];    }];    //命令执行的过程    [[command.executing skip:1] subscribeNext:^(NSNumber * _Nullable x) {        if ([x boolValue]) {            NSLog(@"显示等待....");        }else{            NSLog(@"移动等待");        }    }];    //拿到最新的信号    [command.executionSignals.switchToLatest subscribeNext:^(id  _Nullable x) {        NSLog(@"%@",x);    }];    [[self.btn rac_signalForControlEvents:UIControlEventTouchUpInside] subscribeNext:^(__kindof UIControl * _Nullable x) {        //执行命令        [command execute:nil];    }];

MVVM架构下优化组合信号

#import <Foundation/Foundation.h>#import "ReactiveObjC.h"@interface LoginViewModel : NSObject@property (nonatomic,strong) RACSignal  *loginBtnEnableSignal;@property (nonatomic,strong) RACCommand *loginCommand;@property (nonatomic,strong) NSString *account;@property (nonatomic,strong) NSString *pwd;@end

////  LoginViewModel.m//  RAC////  Created by WiKi on 2017/10/18.//  Copyright © 2017年 wiki. All rights reserved.//#import "LoginViewModel.h"@implementation LoginViewModel- (instancetype)init{    self =[super init];    if (self) {        [self setUp];    }    return self;}- (void)setUp{    _loginBtnEnableSignal =    [[RACSignal combineLatest:@[RACObserve(self, account),RACObserve(self, pwd)]] reduceEach:^id _Nullable(NSString *account ,NSString *pwd){        return @(account.length && account.length);    }];    //command    //命令    self.loginCommand = [[RACCommand alloc] initWithSignalBlock:^RACSignal * _Nonnull(id  _Nullable input) {        NSLog(@"密码加密");        return [RACSignal createSignal:^RACDisposable * _Nullable(id<RACSubscriber>  _Nonnull subscriber) {            [subscriber sendNext:@"请求登录"];            [subscriber sendCompleted]; //发出命令完成            return nil;        }];    }];    //命令执行的过程    [[self.loginCommand.executing skip:1] subscribeNext:^(NSNumber * _Nullable x) {        if ([x boolValue]) {            NSLog(@"显示等待....");        }else{            NSLog(@"移动等待");        }    }];    //拿到最新的信号    [self.loginCommand.executionSignals.switchToLatest subscribeNext:^(id  _Nullable x) {        NSLog(@"%@",x);    }];}@end

    RAC(self.loginViewModel,account) = self.field.rac_textSignal;    RAC(self.loginViewModel,pwd)     = self.field2.rac_textSignal;    RAC(_btn,enabled)                = self.loginViewModel.loginBtnEnableSignal;    [[self.btn rac_signalForControlEvents:UIControlEventTouchUpInside] subscribeNext:^(__kindof UIControl * _Nullable x) {        //执行命令        [_loginViewModel.loginCommand execute:nil];    }];