Sending csv file from Apple Watch to Phone - nothing happening - swift

Question

I have this function in the Watchkit Extension's InterfaceController...
func createAndSendCSV(data: Array<String>) {
var csvText = "time, data\n"
let fileName = "\(startTime).csv"
let path = NSURL(fileURLWithPath: NSTemporaryDirectory()).appendingPathComponent(fileName)
for row in data {
csvText += row
}
do {
try csvText.write(to: path!, atomically: true, encoding: String.Encoding.utf8)
WCSession.default.transferFile(path!, metadata: ["time": startTime])
} catch {
print("Failed to create file")
print("\(error)")
}
}
that is called when the user stops the app on the watch. I know the function is triggered because I can add a print statement in the do catch showing that it was successful.
On ViewController I have the below which isn't much beyond making sure the session is activated and then trying to work with the file that was sent. I don't see any errors but I also don't see my print test message.
I'm trying to use a CSV file to transfer data as I can't send via sendMessage due to size of message. Anyone know why it might not be working?
import UIKit
import WatchConnectivity
class ViewController: UIViewController, WCSessionDelegate {
override func viewDidLoad() {
super.viewDidLoad()
if (WCSession.isSupported()) {
let session = WCSession.default
session.delegate = self
session.activate()
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func session(_ session: WCSession, didReceive file: WCSessionFile) {
DispatchQueue.main.async() {
do {
print("test")
let contents = try String(contentsOf: file.fileURL, encoding: .utf8)
self.sendData(data: contents)
} catch {
print("File Read Error for file \(String(describing: file.metadata))")
}
}
}
func sendData(data: String) {
print(data)
}
// Not used but needs to exist
func session(_ session: WCSession, activationDidCompleteWith activationState: WCSessionActivationState, error: Error?) {
}
func sessionDidBecomeInactive(_ session: WCSession) {
}
func sessionDidDeactivate(_ session: WCSession) {
}
}

Answer 1

The method you are using transferFile(_:metadata:) runs asynchronously and gets throttled by the system to accommodate Apple Watch’s limits on performance and power. You should be able to check the status of the
outstandingFileTransfers property to ensure you are setting up the transfer correctly, but beyond that you may need to rethink how you are sharing data between the two devices.