RAC的mapReplace值操作

值操作—mapReplace：

// 逐一操作单个信号值，统一替换为一个值 
// map遇到错误的时候会无一例外的返回这个错误,并立即结束信号。
RACSignal *signalA = [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
  [subscriber sendNext:@1];
  [subscriber sendNext:@2];
  [subscriber sendNext:@3];
  [subscriber sendNext:@4];
  [subscriber sendCompleted];
  return [RACDisposable disposableWithBlock:^{
    NSLog(@"完成");
  }];
}];


RACSignal *signalB = [signalA mapReplace:@8];
[[signalB subscribeNext:^(id x) {
  NSLog(@"subscribeNext:%@",x);
}] dispose];

执行结果:

2021-04-14 14:38:17.763081+0800 xxxxx[3049:927533] subscribeNext:8

2021-04-14 14:38:17.763162+0800 xxxxx[3049:927533] subscribeNext:8

2021-04-14 14:38:17.763194+0800 xxxxx[3049:927533] subscribeNext:8

2021-04-14 14:38:17.763218+0800 xxxxx[3049:927533] subscribeNext:8

2021-04-14 14:38:17.764598+0800 xxxxx[3049:927533] 完成