详解如何使用ReactiveObjC

概述
RAC架构框架图

信号流程

基本使用
1、基本控件
UITextField
//监听文本输入
[[_textField rac_textSignal] subscribeNext:^(NSString _Nullable x) {
NSLog(@”%@”,x);
}];
/可根据自己想要监听的事件选择
[[_textField rac_signalForControlEvents:UIControlEventEditingChanged] subscribeNext:^(__kindof UIControl _Nullable x) {
NSLog(@”%@”,x);
}];
//添加条件 — 下面表示输入文字长度 > 10 时才会调用subscribeNext
[[_textField.rac_textSignal filter:^BOOL(NSString _Nullable value) {
return value.length > 10;
}] subscribeNext:^(NSString _Nullable x) {
NSLog(@”输入框内容：%@”, x); }];
UIButton
/监听按钮点击事件
[[_btn rac_signalForControlEvents:UIControlEventTouchUpInside] subscribeNext:^(__kindof UIControl _Nullable x) {
NSLog(@”—>%@”,x);
}];
计时器（interval、delay）
/类似timer
@weakify(self)
self.disposable = [[RACSignal interval:2 onScheduler:[RACScheduler mainThreadScheduler]] subscribeNext:^(NSDate _Nullable x) {
@strongify(self)
NSLog(@”时间：%@”, x); // x 是当前的时间
//关闭计时器
[self.disposable dispose];
}];
//延时
[[[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
[subscriber sendNext:@”延时2秒”];
return nil;<br>}] delay:2] subscribeNext:^(id x) {

        NSLog(@"-->%@",x);
}];

2、监听属性变化
//监听self的name属性
[RACObserve(self, name) subscribeNext:^(id _Nullable x) {
NSLog(@”属性的改变—>%@”,x);
}];
[[self rac_valuesForKeyPath:@”name” observer:self] subscribeNext:^(id _Nullable x) {
NSLog(@”属性的改变—>%@”, x);
}];
//此处RAC宏相当于让_label订阅了_textField的文本变化信号
//赋值给label的text属性
RAC(_label, text) = _textField.rac_textSignal;
3、遍历数组和字典
//遍历数组
NSArray array = @[@”1”, @”2”, @”3”, @”4”, @”5”];
[array.rac_sequence.signal subscribeNext:^(id _Nullable x) {
NSLog(@”内容—>%@”, x)<br>}]
4、监听 Notification 通知事件
[[[NSNotificationCenter defaultCenter] rac_addObserverForName:@”notification” object:nil] subscribeNext:^(NSNotification _Nullable x) {
NSLog(@”—>%@”, x);
}];
5、代替Delegate代理
//监听按钮点击方法的信号
//当执行完btnClickAction后会执行此订阅
[[self rac_signalForSelector:@selector(btnClickAction:)] subscribeNext:^(RACTuple _Nullable x) {
NSLog(@”—>%@”, x);
}];
-(void) btnClickAction:(UIButton )btn
{
NSLog(@”按钮点击”);
}
二、RAC常用类
RACSignal
RACSignal signal = [RACSignal createSignal:^RACDisposable _Nullable(id<RACSubscriber> _Nonnull subscriber) {
[subscriber sendNext:@”???????”];
[subscriber sendCompleted];
return [RACDisposable disposableWithBlock:^{
NSLog(@”销毁了???”);
}];
}];
[signal subscribeNext:^(id _Nullable x) {
NSLog(@”%@”,x);
RACSubject(可发送信号也可以订阅信号)

RACTuple（元组）— 其内部就是封装了数组，用起来跟数组差不多
//通过定值创建RACTuple
RACTuple tuple = [RACTuple tupleWithObjects:@”1”, @”2”, @”3”, nil];
//利用 RAC 宏快速封装
RACTuple tuple2 = RACTuplePack(@”1”, @”2”, @”3”);
//从别的数组中获取内容
RACTuple *tuple3 = [RACTuple tupleWithObjectsFromArray:@[@”1”, @”2”, @”3”]];

NSLog(@"元组-->%@", tuple3[0]);
NSLog(@"第一个元素-->%@", [tuple3 first]);
NSLog(@"最后一个元素-->%@", [tuple3 last]);

RACMulticastConnection — 用于当一个信号，被多次订阅时，为了保证创建信号时，避免多次调用创建信号中的block
RACSignal signal1 = [RACSignal createSignal:^RACDisposable _Nullable(id<RACSubscriber> _Nonnull subscriber) {
[subscriber sendNext:@”signal1—>???????”];
[subscriber sendCompleted];
return [RACDisposable disposableWithBlock:^{
NSLog(@”signal1销毁了”);
}];
}];

   RACMulticastConnection *connection = [signal1 publish];
   [connection.signal subscribeNext:^(id  _Nullable x) {
       NSLog(@"subscribeNext-->1");
   }];
   [connection.signal subscribeNext:^(id  _Nullable x) {
       NSLog(@"subscribeNext-->2");
   }];
   [connection.signal subscribeNext:^(id  _Nullable x) {
       NSLog(@"subscribeNext-->3");
   }];
   [connection connect];

RACCommand — 可以监听信号的状态等
NSString input = @”执行”;
RACCommand command = [[RACCommand alloc] initWithSignalBlock:^RACSignal _Nonnull(id _Nullable input) {
NSLog(@”input—>%@”,input);
return [RACSignal createSignal:^RACDisposable _Nullable(id<RACSubscriber> _Nonnull subscriber) {
[subscriber sendNext:@”???????”];
[subscriber sendError:[NSError errorWithDomain:@”error” code:-1 userInfo:nil]];
// [subscriber sendCompleted];
return [RACDisposable disposableWithBlock:^{
NSLog(@”signal销毁了”);
}];
}];
}];
[command.executionSignals subscribeNext:^(RACSignal _Nullable x) {
NSLog(@”executionSignals—>%@”,x);
[x subscribeNext:^(id _Nullable x) {
NSLog(@”executionSignals—>subscribeNext—>%@”,x);
}];
}];
[[command.executionSignals switchToLatest] subscribeNext:^(id _Nullable x) {
NSLog(@”switchToLatest—>%@”,x);
}];
[command.executing subscribeNext:^(id _Nullable x) {
NSLog(@”executing—>%@”,x);
}];
[command.errors subscribeNext:^(id _Nullable x) {
NSLog(@”errors—>%@”,x);
}];
//开始执行
[command execute:input];
三、高级函数使用
1、连接信号、合并信号等
首先创建两个信号signal1和signal2来演示
RACSignal signal1 = [RACSignal createSignal:^RACDisposable _Nullable(id<RACSubscriber> _Nonnull subscriber) {
[subscriber sendNext:@”signal1—>???????”];
[subscriber sendCompleted];
return [RACDisposable disposableWithBlock:^{
NSLog(@”signal1销毁了”);
}];
}];
RACSignal signal2 = [RACSignal createSignal:^RACDisposable * _Nullable(id<RACSubscriber> _Nonnull subscriber) {
[subscriber sendNext:@”signal2—>???????”];
[subscriber sendCompleted];
return [RACDisposable disposableWithBlock:^{
NSLog(@”signal2销毁了”);
}];
}];
1.1、 concat — 当多个信号发出的时候，有顺序的接收信号

一个信号signal3去监听signal1和signal2，必须是接收signal1完后才会接收signal2
RACSignal *signal3 = [signal1 concat:signal2];
[signal3 subscribeNext:^(id _Nullable x) {
NSLog(@”signal3—>%@”,x);
}];
1.2、 combineLatestWith — 将多个信号合并起来，并且拿到各个信号的最新的值,必须每个合并的signal至少都有过一次sendNext，才会触发合并的信号(订阅者每次接收的参数都是所有信号的最新值),不论触发哪个信号都会触发合并的信号

一个信号signal3去监听signal1和signal2，每次回调两个信号的最新值
RACSignal *signal3 = [signal1 combineLatestWith:signal2];
[signal3 subscribeNext:^(id _Nullable x) {
NSLog(@”%@”,x);
}];
PS：注释signal1的sendNext方法，直接销毁了，所以每个singal必须有sendNext方法

1.3、 then — 用于连接两个信号，等待第一个信号完成，才会连接then返回的信号
RACSignal signal3 = [signal1 then:^RACSignal _Nonnull{
return signal2;
}];
[signal3 subscribeNext:^(id _Nullable x) {
NSLog(@”signal3—>%@”,x);
}];
1.4、 merge — 把多个信号合并为一个信号来监听，任何一个信号有新值的时候就会调用

一个信号signal3去监听signal1和signal2，每次回调一个信号
RACSignal *signal3 = [signal1 merge:signal2];
[signal3 subscribeNext:^(id _Nullable x) {
NSLog(@”signal3—>%@”,x);
}];
1.5、 zipWith — 把两个信号压缩成一个信号，只有当两个信号都发出信号内容时，才会触发

一个信号signal3去监听signal1和signal2，但必须两个信号都有发出（不需要同时，例如signal1信号发出了，signal2信号等了10秒之后发出，那么signal3的订阅回调是等signal2信号发出的那一刻触发）
RACSignal signal3 = [signal1 zipWith:signal2];
[signal3 subscribeNext:^(id _Nullable x) {
NSLog(@”signal3—>%@”,x);
}];
1.6、 reduce 聚合 — 把多个信号的值按照自定义的组合返回
RACSignal signal3 = [RACSignal combineLatest:@[signal1,signal2] reduce:^id(NSString s1 ,NSString s2){
return [NSString stringWithFormat:@”%@ %@”,s1,s2];
}];
[signal3 subscribeNext:^(id x) {
NSLog(@”%@”,x);
}];
2、flattenMap & map 映射
flattenMap 的底层实现是通过bind实现的

map 的底层实现是通过 flattenMap 实现的
//map事例
[[_textField.rac_textSignal map:^id _Nullable(NSString _Nullable value) {
return [NSString stringWithFormat:@”%@???????”,value];
}] subscribeNext:^(id _Nullable x) {
NSLog(@”—>%@”,x);
}] ;
//flattenMap事例
[[_textField.rac_textSignal flattenMap:^__kindof RACSignal _Nullable(NSString _Nullable value) {
return [RACSignal createSignal:^RACDisposable _Nullable(id<RACSubscriber> _Nonnull subscriber) {
[subscriber sendNext:[NSString stringWithFormat:@”%@???????”,value]];
[subscriber sendCompleted];
return [RACDisposable disposableWithBlock:^(){}];
}];
}] subscribeNext:^(id _Nullable x) {
NSLog(@”—>%@”,x);
}] ;
3、filter — 过滤、ignore — 忽略、distinctUntilChanged — 忽略相同
filter、ignore
//map事例
[[_textField.rac_textSignal map:^id _Nullable(NSString _Nullable value) {
return [NSString stringWithFormat:@”%@???????”,value];
}] subscribeNext:^(id _Nullable x) {
NSLog(@”—>%@”,x);
}] ;
//flattenMap事例
[[_textField.rac_textSignal flattenMap:^__kindof RACSignal _Nullable(NSString _Nullable value) {
return [RACSignal createSignal:^RACDisposable _Nullable(id<RACSubscriber> _Nonnull subscriber) {
[subscriber sendNext:[NSString stringWithFormat:@”%@???????”,value]];
[subscriber sendCompleted];
return [RACDisposable disposableWithBlock:^(){}];
}];
}] subscribeNext:^(id _Nullable x) {
NSLog(@”—>%@”,x);
}] ;
distinctUntilChanged
RACSubject *subject = [RACSubject subject];
[[subject distinctUntilChanged] subscribeNext:^(id _Nullable x) {
NSLog(@”—>%@”,x);
}];
[subject sendNext:@”123”];
[subject sendNext:@”123”];
[subject sendNext:@”123”];
[subject sendNext:@”??????”];
[subject sendNext:@”??????”];
[subject sendCompleted];

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