skip:跳躍前面幾個信號值
RACSubject *subject = [RACSubject subject];
? ? // 跳躍幾個值
? ? [[subject skip:2] subscribeNext:^(id? _Nullable x) {
? ? ? ? NSLog(@"%@",x);
? ? }];
? ? [subject sendNext:@"11111"];
? ? [subject sendNext:@"11211"];
? ? [subject sendNext:@"11311"];
? ? [subject sendNext:@"11411"];
打痈潮： 11311 +?11411
