With ReactiveCocoa bind to inverse of BOOL

Question

I would like to do the opposite of the following code:

RAC(self.activityIndicator, hidden) = RACObserve(self.playButton, selected);

When the play button is selected the activity indicator should be NOT hidden.

What is the best way to do this using ReactiveCocoa?

Answer 1

There's a signal operator for this, -not.

RAC(self.activityIndicator, hidden) = [RACObserve(self.playButton, selected) not];

Answer 2

map: is what you need.

RAC(self.activityIndicator, hidden) = [RACObserve(self.playButton, selected) map:^id(id value) {
    return @(![value boolValue]);
}];

This transforms the signal into another one based on what you return from the map function.

Answer 3

In newer versions of ReactiveCocoa/ReactiveSwift (v6.2.1) it will look like this:

var isButtonEnabled = MutableProperty<Bool>(true)

myImageView.reactive.isHidden <~ isButtonEnabled.negate()