呼叫WebAPI

取得資料 (使用HttpClient)

var uri = "https://api.domain.com/v1/products/1";

HttpClient _httpClient = new HttpClient();

public async Task<IEnumerable<Person>> GetPeople()
{
    var result = await _httpClient.GetAsync(BASE_URI);
    var peopleJson = await result.Content.ReadAsStringAsync();

    return JsonConvert.DeserializeObject<IEnumerable<Person>>(peopleJson);
}

上傳資料

public async Task<bool> CreatePerson(Person person)
{
    var personJson = JsonConvert.SerializeObject(person);
    var content = new StringContent(personJson, Encoding.UTF8, "application/json");

    //add a header
    client.DefaultRequestHeaders.Authorization = new System.Net.Http.Headers.AuthenticationHeaderValue("Bearer", "my_access_token");

client.Headers.Add("key", "value"); // For any other types of headers.

    var result = await _httpClient.PostAsync(BASE_URI, content);

    return result.IsSuccessStatusCode;
}

useful links

https://mallibone.com/post/implementing-a-cross-platform-http-client-in-the-pcl-to-consume-your-aspnet-web-api-backend-on-azure
https://github.com/svswaminathan/xamarin-forms-httpclient-sample
https://brax.tv/platform/xamarin-forms/json-with-httpclient-and-json-net

https://xamarinhelp.com/connecting-remote-database-xamarin-forms/