Xamarin Certification Xamarin Data and Services 1 — Questions and Answers
Question 1: Which NuGet package provides SQLite database access in Xamarin cross-platform apps?
- sqlite-net-pcl (Correct answer)
- System.Data.SQLite
- EntityFrameworkCore.Sqlite
- Mono.Data.Sqlite
Correct answer: sqlite-net-pcl
sqlite-net-pcl (SQLite-Net) is the standard lightweight ORM for SQLite in Xamarin, supporting iOS and Android via a single PCL/NuGet.
Question 2: In Xamarin, which HttpClient handler is recommended for best performance on iOS?
- NSUrlSessionHandler (Correct answer)
- HttpClientHandler
- ModernHttpClient
- CFNetworkHandler
Correct answer: NSUrlSessionHandler
NSUrlSessionHandler uses the native iOS networking stack, providing better performance, TLS support, and HTTP/2 compared to the managed handler.
Question 3: What is the recommended way to make HTTP REST calls in shared Xamarin code?
- System.Net.Http.HttpClient (Correct answer)
- NSURLConnection
- OkHttp
- WebClient
Correct answer: System.Net.Http.HttpClient
HttpClient from System.Net.Http is the cross-platform HTTP client available in .NET Standard and works in shared Xamarin code.
Question 4: Which Xamarin.Essentials API provides cross-platform access to the device's network connectivity status?
- Connectivity (Correct answer)
- NetworkInfo
- Reachability
- NetworkAccess
Correct answer: Connectivity
Xamarin.Essentials Connectivity class exposes NetworkAccess and ConnectionProfiles to check current network state cross-platform.
Question 5: In Xamarin, which pattern ensures HTTP API calls do not block the main thread?
- async/await with Task-returning methods (Correct answer)
- Thread.Start with callbacks
- BackgroundWorker
- Parallel.For
Correct answer: async/await with Task-returning methods
Using async/await with HttpClient.GetAsync and similar Task-returning methods ensures network I/O is non-blocking and the UI remains responsive.
Question 6: Which library is commonly used for JSON serialization and deserialization in Xamarin applications?
- Newtonsoft.Json (Json.NET) (Correct answer)
- System.Xml.Serialization
- Google.Gson
- Codable
Correct answer: Newtonsoft.Json (Json.NET)
Newtonsoft.Json (Json.NET) is the most widely used .NET JSON library and works seamlessly in Xamarin shared and platform code.
Xamarin Certification Xamarin Data and Services 1
Which NuGet package provides SQLite database access in Xamarin cross-platform apps?