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iOS tv-casting-app: simplified discovery and connection APIs
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@sharadb-amazon
sharadb-amazon committed Jan 7, 2024
1 parent 827f6ca commit 13453ba
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284 changes: 273 additions & 11 deletions examples/tv-casting-app/APIs.md
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Original file line number Diff line number Diff line change
Expand Up @@ -292,21 +292,38 @@ client's lifecycle:
productAttestationIntermediateCert: KPAI_FFF1_8000_Cert_Array)
}

func castingApp(_ sender: Any, didReceiveRequestToSignCertificateRequest csrData: Data) -> Data {
var privateKey = Data()
privateKey.append(kDevelopmentDAC_PublicKey_FFF1_8001);
privateKey.append(kDevelopmentDAC_PrivateKey_FFF1_8001);

let privateKeyRef: SecKey = SecKeyCreateWithData(privateKey as NSData,
func castingApp(_ sender: Any, didReceiveRequestToSignCertificateRequest csrData: Data, outRawSignature: AutoreleasingUnsafeMutablePointer<NSData>) -> MatterError {
Log.info("castingApp didReceiveRequestToSignCertificateRequest")

// get the private SecKey
var privateKeyData = Data()
privateKeyData.append(kDevelopmentDAC_PublicKey_FFF1_8001);
privateKeyData.append(kDevelopmentDAC_PrivateKey_FFF1_8001);
let privateSecKey: SecKey = SecKeyCreateWithData(privateKeyData as NSData,
[
kSecAttrKeyType: kSecAttrKeyTypeECSECPrimeRandom,
kSecAttrKeyClass: kSecAttrKeyClassPrivate,
kSecAttrKeySizeInBits: 256
] as NSDictionary, nil)!

let _:Unmanaged<SecKey> = Unmanaged<SecKey>.passRetained(privateKeyRef);
// sign csrData to get asn1SignatureData
var error: Unmanaged<CFError>?
let asn1SignatureData: CFData? = SecKeyCreateSignature(privateSecKey, .ecdsaSignatureMessageX962SHA256, csrData as CFData, &error)
if(error != nil)
{
Log.error("Failed to sign message. Error: \(String(describing: error))")
return MATTER_ERROR_INVALID_ARGUMENT
}
else if (asn1SignatureData == nil)
{
Log.error("Failed to sign message. asn1SignatureData is nil")
return MATTER_ERROR_INVALID_ARGUMENT
}

// use SecKey above to sign csrData and return resulting value
// convert ASN.1 DER signature to SEC1 raw format
return MTRCryptoUtils.ecdsaAsn1SignatureToRaw(withFeLengthBytes: 32,
asn1Signature: asn1SignatureData!,
outRawSignature: &outRawSignature.pointee)
}
```

Expand All @@ -319,6 +336,7 @@ On Linux, create an `AppParameters` object using the
`RotatingDeviceIdUniqueIdProvider`, `LinuxCommissionableDataProvider`,
`CommonCaseDeviceServerInitParamsProvider`, `ExampleDACProvider` and
`DefaultDACVerifier`, and call `CastingApp::GetInstance()->Initialize` with it.
Then, call `Start` on the `CastingApp`.

```c
LinuxCommissionableDataProvider gCommissionableDataProvider;
Expand Down Expand Up @@ -357,7 +375,8 @@ int main(int argc, char * argv[]) {
On Android, create an `AppParameters` object using the
`rotatingDeviceIdUniqueIdProvider`, `commissioningDataProvider`, `dacProvider`
and `DataProvider<ConfigurationManager>`, and call
`CastingApp.getInstance().initialize` with it.
`CastingApp.getInstance().initialize` with it. Then, call `start` on the
`CastingApp`

```java
public static MatterError initAndStart(Context applicationContext) {
Expand Down Expand Up @@ -406,9 +425,73 @@ func initialize() -> MatterError {
}
```

After initialization, on iOS, call `start` and `stop` on the `MTRCastingApp`
shared instance when the App sends the
`UIApplication.didBecomeActiveNotification` and
`UIApplication.willResignActiveNotification`

```objectivec
struct TvCastingApp: App {
let Log = Logger(subsystem: "com.matter.casting", category: "TvCastingApp")
@State
var firstAppActivation: Bool = true

var body: some Scene {
WindowGroup {
ContentView()
.onAppear(perform: {
let err: Error? = MTRInitializationExample().initialize()
if err != nil
{
self.Log.error("MTRCastingApp initialization failed \(err)")
return
}
})
.onReceive(NotificationCenter.default.publisher(for: UIApplication.didBecomeActiveNotification)) { _ in
self.Log.info("TvCastingApp: UIApplication.didBecomeActiveNotification")
if let castingApp = MTRCastingApp.getSharedInstance()
{
castingApp.start(completionBlock: { (err : Error?) -> () in
if err != nil
{
self.Log.error("MTRCastingApp start failed \(err)")
}
})
}
}
.onReceive(NotificationCenter.default.publisher(for: UIApplication.willResignActiveNotification)) { _ in
self.Log.info("TvCastingApp: UIApplication.willResignActiveNotification")
if let castingApp = MTRCastingApp.getSharedInstance()
{
castingApp.stop(completionBlock: { (err : Error?) -> () in
if err != nil
{
self.Log.error("MTRCastingApp stop failed \(err)")
}
})
}
}
} // WindowGroup
} // body
} // App
```

Note about on-device cache: The Casting App maintains an on-device cache
containing information about the Casting Players it has connected with so far.
This cached information allows the Casting App to connect with Casting Players
(that it had previously connected with) faster and using fewer resources, by
potentially skipping the longer commissioning process and instead, simply
re-establishing the CASE session. This cache can be cleared by calling the
`ClearCache` API on the `CastingApp`, say when the user signs out of the app.
See API and its documentation for [Linux](tv-casting-common/core/CastingApp.h),
Android and
[iOS](darwin/MatterTvCastingBridge/MatterTvCastingBridge/MTRCastingApp.h).

### Discover Casting Players

_{Complete Discovery examples: [Linux](linux/simple-app-helper.cpp)}_
_{Complete Discovery examples: [Linux](linux/simple-app-helper.cpp) |
[Android](android/App/app/src/main/java/com/matter/casting/DiscoveryExampleFragment.java)
| [iOS](darwin/TvCasting/TvCasting/MTRDiscoveryExampleViewModel.swift)}_

The Casting Client discovers `CastingPlayers` using Matter Commissioner
discovery over DNS-SD by listening for `CastingPlayer` events as they are
Expand Down Expand Up @@ -439,6 +522,111 @@ public:
};
```

On Android, implement the `CastingPlayerDiscovery.CastingPlayerChangeListener`.

```java
private static final CastingPlayerDiscovery.CastingPlayerChangeListener castingPlayerChangeListener =
new CastingPlayerDiscovery.CastingPlayerChangeListener() {
private final String TAG = CastingPlayerDiscovery.CastingPlayerChangeListener.class.getSimpleName();

@Override
public void onAdded(CastingPlayer castingPlayer) {
Log.i(TAG, "onAdded() Discovered CastingPlayer deviceId: " + castingPlayer.getDeviceId());
// Display CastingPlayer info on the screen
new Handler(Looper.getMainLooper()).post(() -> {
arrayAdapter.add(castingPlayer);
});
}

@Override
public void onChanged(CastingPlayer castingPlayer) {
Log.i(TAG, "onChanged() Discovered changes to CastingPlayer with deviceId: " + castingPlayer.getDeviceId());
// Update the CastingPlayer on the screen
new Handler(Looper.getMainLooper()).post(() -> {
final Optional<CastingPlayer> playerInList = castingPlayerList.stream().filter(node -> castingPlayer.equals(node)).findFirst();
if (playerInList.isPresent()) {
Log.d(TAG, "onChanged() Updating existing CastingPlayer entry " + playerInList.get().getDeviceId() + " in castingPlayerList list");
arrayAdapter.remove(playerInList.get());
}
arrayAdapter.add(castingPlayer);
});
}

@Override
public void onRemoved(CastingPlayer castingPlayer) {
Log.i(TAG, "onRemoved() Removed CastingPlayer with deviceId: " + castingPlayer.getDeviceId());
// Remove CastingPlayer from the screen
new Handler(Looper.getMainLooper()).post(() -> {
final Optional<CastingPlayer> playerInList = castingPlayerList.stream().filter(node -> castingPlayer.equals(node)).findFirst();
if (playerInList.isPresent()) {
Log.d(TAG, "onRemoved() Removing existing CastingPlayer entry " + playerInList.get().getDeviceId() + " in castingPlayerList list");
arrayAdapter.remove(playerInList.get());
}
});
}
};
```

On iOS, implement a `func addDiscoveredCastingPlayers`,
`func removeDiscoveredCastingPlayers` and `func updateDiscoveredCastingPlayers`
which listen to notifications as Casting Players are added, removed, or updated.

```objectivec
@objc
func didAddDiscoveredCastingPlayers(notification: Notification)
{
Log.info("didAddDiscoveredCastingPlayers() called")
guard let userInfo = notification.userInfo,
let castingPlayer = userInfo["castingPlayer"] as? MTRCastingPlayer else {
self.Log.error("didAddDiscoveredCastingPlayers called with no MTRCastingPlayer")
return
}

self.Log.info("didAddDiscoveredCastingPlayers notified of a MTRCastingPlayer with ID: \(castingPlayer.identifier())")
DispatchQueue.main.async
{
self.displayedCastingPlayers.append(castingPlayer)
}
}

@objc
func didRemoveDiscoveredCastingPlayers(notification: Notification)
{
Log.info("didRemoveDiscoveredCastingPlayers() called")
guard let userInfo = notification.userInfo,
let castingPlayer = userInfo["castingPlayer"] as? MTRCastingPlayer else {
self.Log.error("didRemoveDiscoveredCastingPlayers called with no MTRCastingPlayer")
return
}

self.Log.info("didRemoveDiscoveredCastingPlayers notified of a MTRCastingPlayer with ID: \(castingPlayer.identifier())")
DispatchQueue.main.async
{
self.displayedCastingPlayers.removeAll(where: {$0 == castingPlayer})
}
}

@objc
func didUpdateDiscoveredCastingPlayers(notification: Notification)
{
Log.info("didUpdateDiscoveredCastingPlayers() called")
guard let userInfo = notification.userInfo,
let castingPlayer = userInfo["castingPlayer"] as? MTRCastingPlayer else {
self.Log.error("didUpdateDiscoveredCastingPlayers called with no MTRCastingPlayer")
return
}

self.Log.info("didUpdateDiscoveredCastingPlayers notified of a MTRCastingPlayer with ID: \(castingPlayer.identifier())")
if let index = displayedCastingPlayers.firstIndex(where: { castingPlayer.identifier() == $0.identifier() })
{
DispatchQueue.main.async
{
self.displayedCastingPlayers[index] = castingPlayer
}
}
}
```

Finally, register these listeners and start discovery.

On Linux, register an instance of the `DiscoveryDelegateImpl` with
Expand All @@ -462,9 +650,50 @@ chip::DeviceLayer::PlatformMgr().RunEventLoop();
...
```

On Android, add the implemented `castingPlayerChangeListener` as a listener to
the singleton instance of `MatterCastingPlayerDiscovery` to listen to changes in
the discovered CastingPlayers and call `startDiscovery`.

```java
MatterError err = MatterCastingPlayerDiscovery.getInstance().addCastingPlayerChangeListener(castingPlayerChangeListener);
if (err.hasError()) {
Log.e(TAG, "startDiscovery() addCastingPlayerChangeListener() called, err Add: " + err);
return false;
}

// Start discovery
Log.i(TAG, "startDiscovery() calling CastingPlayerDiscovery.startDiscovery()");
err = MatterCastingPlayerDiscovery.getInstance().startDiscovery(DISCOVERY_TARGET_DEVICE_TYPE);
if (err.hasError()) {
Log.e(TAG, "Error in startDiscovery(): " + err);
return false;
}
```

On iOS, register the listeners by calling `addObserver` on the
`NotificationCenter` with the appropriate selector, and then call start on the
`sharedInstance` of MTRCastingPlayerDiscovery.

```objectivec
func startDiscovery() {
NotificationCenter.default.addObserver(self, selector: #selector(self.didAddDiscoveredCastingPlayers), name: NSNotification.Name.didAddCastingPlayers, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(self.didRemoveDiscoveredCastingPlayers), name: NSNotification.Name.didRemoveCastingPlayers, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(self.didUpdateDiscoveredCastingPlayers), name: NSNotification.Name.didUpdateCastingPlayers, object: nil)

MTRCastingPlayerDiscovery.sharedInstance().start()
...
}
```

Note: You will need to connect with a Casting Player as described below to see
the list of Endpoints that they support. Refer to the
[Connection](#connect-to-a-casting-player) section for details on how to
discover available endpoints supported by a Casting Player.

### Connect to a Casting Player

_{Complete Connection examples: [Linux](linux/simple-app-helper.cpp)}_
_{Complete Connection examples: [Linux](linux/simple-app-helper.cpp) |
[iOS](darwin/TvCasting/TvCasting/MTRConnectionExampleViewModel.swift)}_

Each `CastingPlayer` object created during
[Discovery](#discover-casting-players) contains information such as
Expand Down Expand Up @@ -511,6 +740,37 @@ targetCastingPlayer->VerifyOrEstablishConnection(ConnectionHandler,
...
```
On iOS, the Casting Client may call `verifyOrEstablishConnection` on the
`MTRCastingPlayer` object it wants to connect to and handle any `NSErrors` that
may happen in the process.
```objectivec
// VendorId of the MTREndpoint on the MTRCastingPlayer that the MTRCastingApp desires to interact with after connection
let kDesiredEndpointVendorId: UInt16 = 65521;
@Published var connectionSuccess: Bool?;
@Published var connectionStatus: String?;
func connect(selectedCastingPlayer: MTRCastingPlayer?) {
let desiredEndpointFilter: MTREndpointFilter = MTREndpointFilter()
desiredEndpointFilter.vendorId = kDesiredEndpointVendorId
selectedCastingPlayer?.verifyOrEstablishConnection(completionBlock: { err in
self.Log.error("MTRConnectionExampleViewModel connect() completed with \(err)")
if(err == nil)
{
self.connectionSuccess = true
self.connectionStatus = "Connected!"
}
else
{
self.connectionSuccess = false
self.connectionStatus = "Connection failed with \(String(describing: err))"
}
}, desiredEndpointFilter: desiredEndpointFilter)
}
```
### Select an Endpoint on the Casting Player
_{Complete Endpoint selection examples: [Linux](linux/simple-app-helper.cpp)}_
Expand Down Expand Up @@ -704,4 +964,6 @@ void SubscribeToMediaPlaybackCurrentState(matter::casting::memory::Strong<matter
},
kMinIntervalFloorSeconds, kMaxIntervalCeilingSeconds);
}
The Casting client can Shutdown all running Subscriptions by calling the `ShutdownAllSubscriptions` API on the CastingApp. See API and its documentation for [Linux](tv-casting-common/core/CastingApp.h), Android and [iOS](darwin/MatterTvCastingBridge/MatterTvCastingBridge/MTRCastingApp.h).
```
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