title: ReactiveCocoa CombineLatest: and Zip:
body: <p>I have the same problem as this post, <a href="https://stackoverflow.com/questions/20144752/combine-signals-in-reactivecocoa-to-a-new-one-that-fires-when-all-change">Combine signals in ReactiveCocoa to a new one that fires when all change</a></p>
  
  <p>So I changed to use zip: the the odd problem is the second signals data is not latest one. I put a log in the second signal's map code, it's the latest. E.g.</p>
  
  <p>Signal A, Signal B</p>
  
  <pre><code>[self rac_liftSelector:@selector(doTask:) withSignals:[RACSignal zip:@[A, B]      
  reduce^id(NSNumber* a, NSNumber* b){
     a// is updated to latest
     b// is the old value
  }];
  </code></pre>
  
  <p>In Signal B, I put log found b value is updated.
    If I changed back to CombineLatest: b is updated but a is old value and the signal is not triggered.</p>