ios - ReactiveCocoa takeUntil : doesn't send completion?

Question

我正在做一些基本的信号链。按下按钮后，我想等到 loginSignal 完成才能做一些事情。信号完成，但我的 subscribeCompleted: block 没有被调用。

在 loginSignal 上直接订阅 next 和 completion 会按预期工作。那么，为什么 takeUntil: subscribeCompleted: 不起作用？

[[[button rac_signalForControlEvents:UIControlEventTouchUpInside] takeUntil:loginSignal] subscribeCompleted:^{
    NSLog(@"COMPLETE");
    // Do some other stuff
}];

编辑:这是 logAll

的输出

2014-08-15 10:52:56.417 app[88791:60b] <RACDynamicSignal: 0x10c58a120> name:  next: <UIButton: 0x10c68a870; frame = (240 80; 40 40); opaque = NO; autoresize = TM+BM; autoresizesSubviews = NO; tag = 1103; layer = <CALayer: 0x10c6894a0>>
2014-08-15 10:52:56.417 app[88791:60b] <RACDynamicSignal: 0x10c58a120> name:  next: <UIButton: 0x10c68a870; frame = (240 80; 40 40); opaque = NO; autoresize = TM+BM; autoresizesSubviews = NO; tag = 1103; layer = <CALayer: 0x10c6894a0>>
2014-08-15 10:53:02.086 app[88791:410b] <RACDynamicSignal: 0x112e2c4b0> name:  next: 1
2014-08-15 10:53:02.087 app[88791:410b] <RACDynamicSignal: 0x10c6ea5d0> name:  next: 1
2014-08-15 10:53:02.087 app[88791:410b] <RACDynamicSignal: 0x10c6ea5d0> name:  next: 1
2014-08-15 10:53:02.088 app[88791:410b] <RACDynamicSignal: 0x10c6b8830> name:  next: 1
2014-08-15 10:53:02.089 app[88791:410b] <RACDynamicSignal: 0x10c6b8830> name:  next: 1
2014-08-15 10:53:02.089 app[88791:410b] <RACDynamicSignal: 0x10c52e570> name:  next: 1
2014-08-15 10:53:02.090 app[88791:410b] <RACDynamicSignal: 0x10c52e570> name:  next: 1

编辑 2:这是 loginSignal

RACSignal* loginSignal = [[[RACObserve(obj, loginState) distinctUntilChanged] filter:^BOOL(id value) {
    return ([value integerValue] == LOGGEDIN);
}] takeUntil:[self rac_prepareForReuseSignal]];

Answer 1

事实证明，takeUntil: 并不是获得此行为的正确方法。 loginSignal 触发后，它会导致 sendCompleted: 触发多次(因此看起来没有触发？)，即使对于尚未点击的按钮也是如此。更好的方法是 flattenMap: 并发送 loginSignal。

正确的版本:

[[[[[button rac_signalForControlEvents:UIControlEventTouchUpInside] flattenMap:^RACStream *(id value) {
    return loginSignal;
}] take:1] subscribeNext:^(id value){
    // DO STUFF!!!
}];