Trouble sending data from iPhone to WatchOS using Application Context - ios

Question

I am trying to send data from my iOS app to a companion WatchOS app using WCSession. The iOS app was created with NativeScript, thus the need for Objective-C.
When running the apps on both simulators and real devices I receive the following error message:
[WC] WCSession is missing its delegate
I've been messing around with this for a few days but unable to fix this issue.
iOS Objective-C Code (This is being called in Typescript):
#import "SendToWatch.h"
#import <WatchConnectivity/WatchConnectivity.h>
#interface SendToWatch () <WCSessionDelegate>
#end
#implementation SendToWatch
- (void)sendData: (double)value {
if (WCSession.isSupported) {
WCSession *session = [WCSession defaultSession];
session.delegate = self;
[session activateSession];
NSError *error = nil;
NSDictionary *applicationDict = #{#"data":[NSString stringWithFormat:#"%0.2f", value]};
[session updateApplicationContext:applicationDict error:nil];
if (error) {
NSLog(#"%#", error.localizedDescription);
}
}
}
//MARK: - WCSessionDelegate
- (void)session:(WCSession *)session
activationDidCompleteWithState:(WCSessionActivationState)activationState
error:(NSError *)error {
}
- (void)sessionDidBecomeInactive:(WCSession *)session {
NSLog(#"Session Did Become Inactive");
}
- (void)sessionDidDeactivate:(WCSession *)session {
NSLog(#"-- Session Did Deactivate --");
[session activateSession];
}
#end
WatchOS (InterfaceController.m):
#import "InterfaceController.h"
#import <WatchConnectivity/WatchConnectivity.h>
#interface InterfaceController () <WCSessionDelegate>
#end
#implementation InterfaceController
- (void)awakeWithContext:(id)context {
[super awakeWithContext:context];
// Creates a WCSession to allow iPhone connectivity
if ([WCSession isSupported]) {
WCSession *session = [WCSession defaultSession];
session.delegate = self;
[session activateSession];
NSLog(#"-- WCSession Active --");
}
}
- (void)willActivate {
[super willActivate];
NSLog(#"-- Controller Activated --");
}
- (void)didDeactivate {
[super didDeactivate];
NSLog(#"-- Controller Deactive --");
}
//MARK: - WCSessionDelegate
// Receieves the data sent from the iPhone app
- (void)session:(nonnull WCSession *)session didReceiveApplicationContext:(nonnull NSDictionary *)applicationContext {
NSString *receivedData = [applicationContext objectForKey:#"data"];
NSLog(#"-- APPLICATION CONTEXT RECEIVED --");
NSLog(#"-- Received from iOS App: %#", applicationContext);
dispatch_async(dispatch_get_main_queue(), ^{
[self.dataLabel setText:receivedData];
NSLog(#"-- DATA UPDATED --");
});
}
- (void)session:(WCSession *)session activationDidCompleteWithState:(WCSessionActivationState)activationState error:(NSError *)error {
}
#end

Answer 1

You'll need to move your session configuration and activation code
if ([WCSession isSupported]) {
WCSession* session = [WCSession defaultSession];
session.delegate = self;
[session activateSession];
}
to somewhere early in the iOS app's lifecycle, rather than in the sendData message.

Answer 2

To fix this I had to re-write the Objective-C code in typescript using the tns-platform-declarations plugin. The WCSession now has a delegate and is sending data to my companion WatchOS app.