Push Ringing

<key>NSMicrophoneUsageDescription</key>
<string>Lets you talk on calls.</string>
<key>NSCameraUsageDescription</key>
<string>Lets you be seen on video calls.</string>
<key>UIBackgroundModes</key>
<array>
    <string>voip</string>
    <string>audio</string>
</array>

import UIKit
import CometChatPushNotificationsSwift
import CometChatPushNotificationsCalls

final class PushDelegate: NSObject, CometChatPushNotificationsCallsDelegate {

    // The user answered: show the call screen and join. Return false only when the app
    // cannot take the call at all; the SDK then ends the CallKit call.
    // The SDK calls both methods on the main queue.
    func presentCall(_ call: IncomingCall) -> Bool {
        MainActor.assumeIsolated { CallPresenter.shared.show(call) }
        return true
    }

    // The call is over (or never started): take the screen down. CallKit has already been told.
    func callDidEnd(_ call: IncomingCall, reason: CallEndReason) {
        MainActor.assumeIsolated { CallPresenter.shared.end(sessionId: call.sessionId) }
    }
}

import UIKit
import CometChatPushNotificationsCalls

@MainActor
final class CallPresenter {

    static let shared = CallPresenter()

    private var pending: IncomingCall?
    private weak var screen: CallViewController?

    func show(_ call: IncomingCall) {
        if screen?.call.sessionId == call.sessionId { return }
        guard let top = Self.topViewController() else {
            pending = call                     // no window yet: a launch started by the push
            return
        }
        let screen = CallViewController(call: call)
        self.screen = screen
        top.present(screen, animated: false)
    }

    /// Call when your UI comes up, for example from sceneDidBecomeActive(_:) or your root view's onAppear.
    func showPending() {
        guard let call = pending else { return }
        pending = nil
        show(call)
    }

    func end(sessionId: String) {
        if pending?.sessionId == sessionId { pending = nil }
        if screen?.call.sessionId == sessionId { screen?.dismiss(animated: true) }
    }

    private static func topViewController() -> UIViewController? {
        let windows = UIApplication.shared.connectedScenes
            .compactMap { $0 as? UIWindowScene }
            .flatMap { $0.windows }
        var top = (windows.first { $0.isKeyWindow } ?? windows.first)?.rootViewController
        while let presented = top?.presentedViewController { top = presented }
        return top
    }
}

import UIKit
import CometChatCallsSDK
import CometChatPushNotificationsCalls

final class CallViewController: UIViewController {

    let call: IncomingCall
    private let container = UIView()

    init(call: IncomingCall) {
        self.call = call
        super.init(nibName: nil, bundle: nil)
        modalPresentationStyle = .fullScreen
    }

    required init?(coder: NSCoder) { fatalError("init(coder:) is not supported") }

    override func viewDidLoad() {
        super.viewDidLoad()
        container.frame = view.bounds
        container.autoresizingMask = [.flexibleWidth, .flexibleHeight]
        view.addSubview(container)

        let settings = SessionSettingsBuilder()
            .setSessionType(call.isVideo ? .video : .voice)
            .startVideoPaused(!call.isVideo)
            .build()
        CometChatCalls.joinSession(sessionID: call.sessionId, callSetting: settings, container: container,
            onSuccess: { _ in },
            onError: { [weak self] _ in
                DispatchQueue.main.async { self?.dismiss(animated: true) }
            })
    }
}