Swift extensions to ReactiveCocoa to make it easier to work with from Swift.

RACSupport.swift

import Foundation

extension RACSignal {

  func subscribeNextAs<T>(nextClosure: (T?) -> Void) {
    self.subscribeNext {
      (next: AnyObject!) -> () in
      let nextAsT = next as? T
      nextClosure(nextAsT)
    }
  }
  
  func doNextAs<T>(nextClosure: (T?) -> Void) -> RACSignal {
    return self.doNext {
      (next: AnyObject!) -> () in
      let nextAsT = next as? T
      nextClosure(nextAsT)
    }
  }
}

struct RAC {
  var target : NSObject!
  var keyPath : String!
  var nilValue : AnyObject!
  
  init(_ target: NSObject!, _ keyPath: String, nilValue: AnyObject? = nil) {
    self.target = target
    self.keyPath = keyPath
    self.nilValue = nilValue
  }
  
  func assignSignal(signal : RACSignal) {
    signal.setKeyPath(self.keyPath, onObject: self.target, nilValue: self.nilValue)
  }
}

infix operator <~ {}
func <~ (rac: RAC, signal: RACSignal) {
  rac.assignSignal(signal)
}

func RACObserve(target: NSObject!, keyPath: String) -> RACSignal  {
  return target.rac_valuesForKeyPath(keyPath, observer: target)
}