ios - 2 RACCommands 以便一个被禁用而另一个正在执行，反之亦然

Question

我如何创建 2 个 RACCommand，以便在另一个执行时禁用一个，并且反之亦然？

像这样，

_prevTrackCommand = [[RACCommand alloc] initWithEnabled: [_nextTrackCommand.executing not] signalBlock:^RACSignal *(id _) {}];

_nextTrackCommand = [[RACCommand alloc] initWithEnabled: [_prevTrackCommand.executing not] signalBlock:^RACSignal *(id _) {}];

但此代码将不起作用，因为 _nextTrackCommand 在 _prevTrackCommand 初始化时为 nil。

Answer 1

您可以使用一个 RACSubject，它可以用作 RACSignal 但允许您手动转发事件:

RACSubject* commandAActive = [RACSubject subject];
RACSubject* commandBActive = [RACSubject subject];

RACCommand* commandA = [[RACCommand alloc] initWithEnabled:[commandBActive not]
                                        signalBlock:^RACSignal * _Nonnull(id  _Nullable input) {
    // block
}];
RACCommand* commandB = [[RACCommand alloc] initWithEnabled:[commandAActive not]
                                    signalBlock:^RACSignal * _Nonnull(id  _Nullable input) {
   // block
}];

[commandA.executing subscribeNext:^(NSNumber * _Nullable x) {
    [commandAActive sendNext:x];
}];
[commandB.executing subscribeNext:^(NSNumber * _Nullable x) {
    [commandBActive sendNext:x];
}];