RAC的Error操作

将某个值变成一个错误的信号:

RACSignal *signalA = [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
  [subscriber sendNext:@1];
  [subscriber sendNext:@2];
  [subscriber sendNext:@3];
  [subscriber sendNext:@4];
  [subscriber sendNext:@5];
  [subscriber sendCompleted];
  return [RACDisposable disposableWithBlock:^{
      NSLog(@"signalA1完成");
  }];
}];
RACSignal *signalB = [[signalA map:^id(NSNumber *value) {
  if (value.integerValue == 5) {
      return [RACSignal error:[NSError errorWithDomain:@"0" code:0 userInfo:nil]];
  } else {
      return [RACSignal return:value];
  }
}] flatten];

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

[signalB subscribeError:^(NSError *error) {
  NSLog(@"subscribeNext:%@",error.description);
}];

2021-04-15 16:43:49.033757+0800 NetSchool[3863:1105334] subscribeNext:1

2021-04-15 16:43:49.033880+0800 NetSchool[3863:1105334] subscribeNext:2

2021-04-15 16:43:49.033913+0800 NetSchool[3863:1105334] subscribeNext:3

2021-04-15 16:43:49.034021+0800 NetSchool[3863:1105334] subscribeNext:4

2021-04-15 16:43:49.035297+0800 NetSchool[3863:1105334] signalA1完成

2021-04-15 16:43:49.035822+0800 NetSchool[3863:1105334] subscribeNext:Error Domain=0 Code=0 "(null)"

2021-04-15 16:43:49.035866+0800 NetSchool[3863:1105334] signalA1完成