Method on

packages/firebase-database/index.ios.ts:256–276

(eventType: EventType, callback: (data: DataSnapshot, previousChildKey: string) => void, cancelCallbackOrContext?: (a: any) => void | Record<string, any>, context?: Record<string, any>)

	}

	on(eventType: EventType, callback: (data: DataSnapshot, previousChildKey: string) => void, cancelCallbackOrContext?: (a: any) => void | Record<string, any>, context?: Record<string, any>): (a: DataSnapshot, b: string) => void {
		const handle = this.native?.observeEventTypeAndPreviousSiblingKeyWithBlockWithCancelBlock?.(
			toFIRDataEventType(eventType),
			(snapshot, key) => {
				callback(DataSnapshot.fromNative(snapshot), key);
			},
			(error) => {
				cancelCallbackOrContext?.({
					message: error.localizedDescription,
					native: error,
				});
			}
		);
		callback['__fbHandle'] = handle;
		callback['__fbEventType'] = eventType;
		callback['__fbContext'] = context;

		this._handles.set(callback, handle);

		return callback;
	}

	once(eventType: EventType, successCallback?: (a: DataSnapshot, b: string) => any, failureCallbackContext?: (a: any) => void | Record<string, any>): Promise<DataSnapshot> {
		return new Promise((resolve, reject) => {