Disabling UIBarButtonItem with ReactiveCocoa - ios

Question

I'm trying to disable a UIBarButtonItem in my iOS app when a condition has been met.
So in my viewModel I created this signal:
-(RACSignal *)thresholdLimitReachedSignal
{
#weakify(self);
return [RACObserve(self, thresholdLimitReached) filter:^BOOL(id value) {
#strongify(self);
return self.thresholdLimitReached;
}];
}
Then in my viewController I have this:
self.requestNewPinButton.rac_command = [[RACCommand alloc]initWithEnabled:self.viewModel.thresholdLimitReachedSignal
signalBlock:^RACSignal *(id input) {
[self.viewModel.requestNewPinSignal subscribeNext:^(id x) {
//do some stuff here
}];
return [RACSignal empty];
}];
So the UIBarButtonItem is triggered and fires off a requestNewPinSignal which works just fine. Then I flag thresholdLimitReached which causes the thresholdLimitReachedSignal to fire - all good. However the button just does not get disabled and I am not sure why? No matter if I manually set the boolean to true or false inside the thresholdLimitReachedSignal method - button remains enabled!
If I manually subscribe to thresholdLimitReachedSignal
like so:
[self.viewModel.thresholdLimitReachedSignal subscribeNext:^(id x) {
self.requestNewPinButton.enabled = NO;
}];
Then button gets disabled no problem. I'd like to have this signal combined with the requestSignal some how - I thought initWithEnabled:signalBlock did this?

Answer 1

[RACObserve(self, thresholdLimitReached) filter:^BOOL(id value) {
#strongify(self);
return self.thresholdLimitReached;
}];
You're filtering thresholdLimitReachedSignal so that it only ever returns YES, so your button is always going to be enabled. For starters, you could rewrite that like this and avoid the #weakify/#strongify:
[RACObserve(self, thresholdLimitReached) filter:^BOOL(NSNumber *thresholdLimitReached) {
return thresholdLimitReached.boolValue;
}];
But don't do that: if you're using this as the enabled signal, it needs to be a signal of booleans that sends YES when it should be enabled and NO when it should be disabled.
Assuming that your want the button to be disabled when the threshold has been reached, you want something like this:
[[RACCommand alloc] initWithEnabled:[RACObserve(self.viewModel, thresholdLimitReached) not]
signalBlock:...];