Observable 是在 Swift 中观察值的最简单方法

class SomeViewModel {
    /// Public property, that can be read / observed by external classes (e.g. view controller), but not changed.
    var position: Observable<CGPoint> = {
        return positionSubject
    }
    // Or use the helper method Observable.asObservable()
    // lazy var position = positionSubject.asObservable()

    /// Private property, that can be changed / observed inside this view model.
    private let positionSubject = MutableObservable(CGPoint.zero)
}

url.startAccessingSecurityScopedResource()
let observable = Observable([URL]()) {
    url.stopAccessingSecurityScopedResource()
}

//Private Observer
@MutableObservable var text: String = "Test"

//add observer

_text.observe { (newValue, oldValue) in
    print(newValue)
}.add(to: &disposable)
        
//Public Observer

var textObserve: ImmutableObservable<String> {
    return _text
}

position.observe { p in
    // handle new position
}

position.observe(DispatchQueue.main) { p in
// handle new position
}

position.wrappedValue = p

position.observe {
    // This will stop all observers added to `disposal`
    self.disposal.dispose()
}.add(to: &disposal)

disposable = position.observe { p in

position.observe { }.add(to: &disposal)

position.observe { [weak self] position in

pod 'Observable'

dependencies: [
    .package(url: "https://github.com/roberthein/Observable", from: "VERSION")
]