RXSwift rx实现原理

.rx的实现原理
关联类型。
主要实现ReactiveCompatible协议，实现了这个协议的都会有rx。万物皆rx

/// Extend NSObject with `rx` proxy.
extension ReactiveCompatible {
    /// Reactive extensions.
    public static var rx: Reactive<Self>.Type {
        get {
            return Reactive<Self>.self
        }
        set {
            // this enables using Reactive to "mutate" base type
        }
    }

    /// Reactive extensions.
    public var rx: Reactive<Self> {
        get {
            return Reactive(self)
        }
        set {
            // this enables using Reactive to "mutate" base object
        }
    }
}

extension NSObject: ReactiveCompatible { }