CombineLatest、Zip和Merge的区别

信号触发方式

merge

只要merge之后生成的信号被订阅就会自动触发所有压缩信号的订阅回调，如果靠前的信号出现了error后面的信号不再发送。

核心方法：- (instancetype)flatten
值：多次收到，分开的

 1
 2

RACSignal *s1 = [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
  [subscriber sendNext:@"1"];
    return nil;
}];

RACSignal *s2 = [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
    [subscriber sendNext:@"2"];
    return nil;
}];

[[RACSignal merge:@[s1,s2]] subscribeNext:^(id x) {
    NSLog(@"%@",x);
}];

combineLatest

必须等到所有的信号都成功发送才能触发combineLatest生成的新信号的订阅回调。如果中间出现有信号error或者complete，新信号将收不到回调。

核心方法： + (instancetype)join:(id<NSFastEnumeration>)streams block:(RACStream * (^)(id, id))block

- (RACSignal *)combineLatestWith:(RACSignal *)signal

值：一次收到，通过RACTuple聚合的

<RACTuple: 0x60000318c780> (
    1,
    2
)

RACSubject *s1 = [RACSubject subject];
[s1 subscribeNext:^(id x) {
    NSLog(@"%@",x);
}];

RACSubject *s2 = [RACSubject subject];
[s2 subscribeNext:^(id x) {
    NSLog(@"%@",x);
}];

[[RACSignal combineLatest:@[s1,s2]] subscribeNext:^(id x) {
    NSLog(@"%@",x);
}];

[s1 sendNext:@"1"];
[s2 sendNext:@"2"];

zip

必须等到所有的信号都成功发送才能触发zip生成的新信号的订阅回调(和combineLatest类似)。如果中间出现有信号error或者complete，新信号将收不到回，和combineLatest不同的是，同一时间返回多个信号的值只取第一个，而combineLatest是取最新的值

//zip
....
void (^sendNext)(void) = ^{
			@synchronized (selfValues) {
				if (selfValues.count == 0) return;
				if (otherValues.count == 0) return;
				//去数组第一个值
				RACTuple *tuple = [RACTuple tupleWithObjects:selfValues[0], otherValues[0], nil];
				[selfValues removeObjectAtIndex:0];
				[otherValues removeObjectAtIndex:0];

				[subscriber sendNext:tuple];
				sendCompletedIfNecessary();
			}
		};
....

//combineLatestWith
...
void (^sendNext)(void) = ^{
			@synchronized (disposable) {
				if (lastSelfValue == nil || lastOtherValue == nil) return;
				[subscriber sendNext:[RACTuple tupleWithObjects:lastSelfValue, lastOtherValue, nil]];
			}
		};
...

核心方法： 1. + (instancetype)join:(id<NSFastEnumeration>)streams block:(RACStream * (^)(id, id))block 2. - (RACSignal *)zipWith:(RACSignal *)signal

值：一次收到，通过RACTuple聚合的

 <RACTuple: 0x600002668e20> (
    1,
    2,
    3
)

RACSignal *s1 = [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
   [subscriber sendNext:@"1"];
    return nil;
}];
RACSignal *s2 = [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
    [subscriber sendNext:@"2"];
    return nil;
}];
RACSignal *s3 = [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
    [subscriber sendNext:@"3"];
    return nil;
}];

RACSignal *zs = [RACSignal zip:@[s1,s2,s3]];

[zs subscribeNext:^(id x) {
    NSLog(@"%@",x);
}];