Apple Watch, WatchKit Extension and main application

Question

There is main application with logic and we extend app to Apple Watch.

After adding target xCode creates 2 more applications: extension with code and watch kit application.

Question: How code from extension can reuse logic of ready and already made main iOS app? How extension app can communicate with main App and send commands.

Answer 1

To communicate to the containing iPhone app you can use

(BOOL)openParentApplication:(NSDictionary *)userInfo
                        reply:(void (^)(NSDictionary *replyInfo,
                                        NSError *error))reply

In your WKInterfaceController

From the Apple Docs

Use this method to communicate with your containing iOS app. Calling the method causes iOS to launch the app in the background (as needed) and call the application:handleWatchKitExtensionRequest:reply: method of its app delegate. That method has the following signature:

- (void)application:(UIApplication *)application handleWatchKitExtensionRequest:(NSDictionary *)userInfo
reply:(void(^)(NSDictionary *replyInfo))reply

The app delegate receives the dictionary you pass into the userInfo parameter and uses it to process whatever request you made. If it provides a reply, WatchKit executes the block you provided in the reply parameter of this method.

Answer 2

At current state of Apple Watch Extension:

• You can share information between iOS main appliation and WatchKit Extension. Use App Groups and NSUserDefaults to access the shared information objects.

• You can not execute code from your iOS app which is trigged from actions on the Apple Watch.

At least not yet.

EDIT: As of Xcode 6.2 Beta 2

It is now possible to communicate with the parent iOS app from Apple Watch.

In WatchKit Extension call the parent application via openParentAppentApplicion. One can pass a value dictionary to the parent application and the parent application can return a value dictionary.

Watchkit Extension:

// Call the parent application from Apple Watch

// values to pass
let parentValues = [
    "value1" : "Test 1",
    "value2" : "Test 2"
]

WKInterfaceController.openParentApplication(parentValues, reply: { (replyValues, error) -> Void in
    println(replyValues["retVal1"])
    println(replyVaiues["retVal2"])
})

iOS App:

// in AppDelegate.swift
func application(application: UIApplication!, handleWatchKitExtensionRequest userInfo: [NSObject : AnyObject]!, reply: (([NSObject : AnyObject]!) -> Void)!) {
    // retrieved parameters from Apple Watch
    println(userInfo["value1"])
    println(userInfo["value2"])

    // pass back values to Apple Watch
    var retValues = Dictionary<String,String>()

    retValues["retVal1"] = "return Test 1"
    retValues["retVal2"] = "return Test 2"

    reply(retValues)
}