How to exchange Realm data between watchOS and iOS ref: http://qiita.com/hsylife/items/26629e65bf66d79cd311

Field.swift

import RealmSwift

public class Field: Object {
    public dynamic var text: String?
}

file0.txt

target 'SampleRealmOnWatchOS3' do
dynamic frameworks
  use_frameworks!
  pod 'RealmSwift'
end

target 'SampleWatchApp_Extension' do
  use_frameworks!
  platform :watchos, '2.0'
  pod 'RealmSwift'
end

post_install do |installer|
  installer.pods_project.targets.each do |target|
    target.build_configurations.each do |config|
      config.build_settings['SWIFT_VERSION'] = '3.0'
    end
  end
end

file2.swift

class ViewController: UIViewController, WCSessionDelegate {

InterfaceController.swift

  func session(_ session: WCSession, didReceiveMessage message: [String : Any], replyHandler: @escaping ([String : Any]) -> Void) {

        if let text = message["text"] as! String?{
            messageLabel.setText(text)
        }

        replyHandler(["reply" : "OK"])
    }

ViewController.swift

func sendMessage(){
        if WCSession.default().isReachable {
            let applicationDict = ["text": messageTextField.text ?? ""]
            WCSession.default().sendMessage(applicationDict,
                                            replyHandler: { replyDict in print(replyDict) },
                                            errorHandler: { error in print(error.localizedDescription)})
        }

    }