Xamarin tvOS:Collectionview未显示REST API响应中的数据？

我在下面的博客中介绍了如何在我的tvOS应用程序中实现

Collectionview

。在本博客中，数据添加到

CityViewDatasource

类中。静态数据添加到此博客上，如下所示：

        Cities.Clear();
        Cities.Add(new CityInfo("City01.jpg", "Houses by Water", false));
        Cities.Add(new CityInfo("City02.jpg", "Turning Circle", true));
        Cities.Add(new CityInfo("City03.jpg", "Skyline at Night", true));
        Cities.Add(new CityInfo("City04.jpg", "Golden Gate Bridge", true));
        Cities.Add(new CityInfo("City05.jpg", "Roads by Night", true));
        Cities.Add(new CityInfo("City06.jpg", "Church Domes", true));
        Cities.Add(new CityInfo("City07.jpg", "Mountain Lights", true));
        Cities.Add(new CityInfo("City08.jpg", "City Scene", false));

 try
        {
            HttpClient client = new HttpClient();
            var response = await client.GetAsync("My REST API");
            if (response.IsSuccessStatusCode)
            {
                var Response = JsonConvert.DeserializeObject(await response.Content.ReadAsStringAsync());
                if (!string.IsNullOrWhiteSpace(Response.ToString()))
                {
                    var category = JsonConvert.DeserializeObject<VideoList>(Response.ToString());
                    Cities.Clear();
                    for (int i = 0; i < category.webContentHBList.Count; i++)
                    {
                        Cities.Add(new CityInfo(category.webContentHBList[i].ImageUrl, category.webContentHBList[i].title, true));
                    }
                }
            }
        }
        catch (Exception e)
        {
            Debug.WriteLine("exception:>>" + e);
        }

我需要通过调用REST API将静态数据更改为动态数据，如下所示：

        Cities.Clear();
        Cities.Add(new CityInfo("City01.jpg", "Houses by Water", false));
        Cities.Add(new CityInfo("City02.jpg", "Turning Circle", true));
        Cities.Add(new CityInfo("City03.jpg", "Skyline at Night", true));
        Cities.Add(new CityInfo("City04.jpg", "Golden Gate Bridge", true));
        Cities.Add(new CityInfo("City05.jpg", "Roads by Night", true));
        Cities.Add(new CityInfo("City06.jpg", "Church Domes", true));
        Cities.Add(new CityInfo("City07.jpg", "Mountain Lights", true));
        Cities.Add(new CityInfo("City08.jpg", "City Scene", false));

 try
        {
            HttpClient client = new HttpClient();
            var response = await client.GetAsync("My REST API");
            if (response.IsSuccessStatusCode)
            {
                var Response = JsonConvert.DeserializeObject(await response.Content.ReadAsStringAsync());
                if (!string.IsNullOrWhiteSpace(Response.ToString()))
                {
                    var category = JsonConvert.DeserializeObject<VideoList>(Response.ToString());
                    Cities.Clear();
                    for (int i = 0; i < category.webContentHBList.Count; i++)
                    {
                        Cities.Add(new CityInfo(category.webContentHBList[i].ImageUrl, category.webContentHBList[i].title, true));
                    }
                }
            }
        }
        catch (Exception e)
        {
            Debug.WriteLine("exception:>>" + e);
        }

试试看
{
HttpClient=新的HttpClient（）；
var response=await client.GetAsync（“我的RESTAPI”）；
if（响应。IsSuccessStatusCode）
{
var Response=JsonConvert.DeserializeObject（wait Response.Content.ReadAsStringAsync（））；
如果（！string.IsNullOrWhiteSpace（Response.ToString（）））
{
var category=JsonConvert.DeserializeObject（Response.ToString（））；
城市。清除（）；
对于（int i=0；i>”+e）；
}

但是当我运行项目时，UI上没有数据，只显示一个空白屏幕。输出窗口中未显示任何错误

---

我已将服务域包括在info.plist的

NSAppTransportSecurity

下。RESTAPI调用成功，我能够获得项目的数量。我添加了一个示例项目供参考。

检查共享代码和项目后，您需要在收到后重新加载数据 api数据及其处理

修改如下：

HttpClient client = new HttpClient();
var response = await client.GetAsync("REST API");
if (response.IsSuccessStatusCode)
{
    var Response = JsonConvert.DeserializeObject(await response.Content.ReadAsStringAsync());
    if (!string.IsNullOrWhiteSpace(Response.ToString()))
    {
        var category = JsonConvert.DeserializeObject<VideoList>(Response.ToString());
        Cities.Clear();
        for (int i = 0; i < category.webContentHBList.Count; i++)
        {
            //Cities.Add(new CityInfo("category.webContentHBList[i].thumbnailImageUrl.Replace(" ","%20"), category.webContentHBList[i].pageTitle, true));
            Cities.Add(new CityInfo("City01.jpg", category.webContentHBList[i].pageTitle, true));
                        
        }
        // reload data after receiving 
        InvokeOnMainThread(() => {
            // manipulate UI controls
            this.ViewController.ReloadData();
        });
    }
}

...

public CityInfo City {
    get { return _city; }
    set {
        _city = value;
        //CityView.Image = UIImage.FromFile (City.ImageFilename);
        CityView.Image = FromUrl(City.ImageFilename);
        // here api url not showing , it's invalid in tvOS 
        // such as using test url , it will show 
        // CityView.Image = FromUrl(https://s1.ax1x.com/2020/06/30/N5sh5R.png)
        CityView.Alpha = (City.CanSelect) ? 1.0f : 0.5f;
        CityTitle.Text = City.Title;
    }
}
#endregion

static UIImage FromUrl(string uri)
{
    using (var url = new NSUrl(uri))
    using (var data = NSData.FromUrl(url))
        return UIImage.LoadFromData(data);
}

...

您可以按如下方式修改

CityCollectionViewCell.cs

：

HttpClient client = new HttpClient();
var response = await client.GetAsync("REST API");
if (response.IsSuccessStatusCode)
{
    var Response = JsonConvert.DeserializeObject(await response.Content.ReadAsStringAsync());
    if (!string.IsNullOrWhiteSpace(Response.ToString()))
    {
        var category = JsonConvert.DeserializeObject<VideoList>(Response.ToString());
        Cities.Clear();
        for (int i = 0; i < category.webContentHBList.Count; i++)
        {
            //Cities.Add(new CityInfo("category.webContentHBList[i].thumbnailImageUrl.Replace(" ","%20"), category.webContentHBList[i].pageTitle, true));
            Cities.Add(new CityInfo("City01.jpg", category.webContentHBList[i].pageTitle, true));
                        
        }
        // reload data after receiving 
        InvokeOnMainThread(() => {
            // manipulate UI controls
            this.ViewController.ReloadData();
        });
    }
}

...

public CityInfo City {
    get { return _city; }
    set {
        _city = value;
        //CityView.Image = UIImage.FromFile (City.ImageFilename);
        CityView.Image = FromUrl(City.ImageFilename);
        // here api url not showing , it's invalid in tvOS 
        // such as using test url , it will show 
        // CityView.Image = FromUrl(https://s1.ax1x.com/2020/06/30/N5sh5R.png)
        CityView.Alpha = (City.CanSelect) ? 1.0f : 0.5f;
        CityTitle.Text = City.Title;
    }
}
#endregion

static UIImage FromUrl(string uri)
{
    using (var url = new NSUrl(uri))
    using (var data = NSData.FromUrl(url))
        return UIImage.LoadFromData(data);
}

...

---

你能看一下for循环中被注释的第一行吗。我需要使用这一行而不是第二行，项目有图像url，我需要在UI上显示特定的图像。我现在取消注释该行，但图像部分为空。通过URL加载图像是否还有其他附加内容？@SreejithSree嗨，动态图像意味着像gif一样的图像？响应中有一个imageurl，我们需要添加根URL以获得完整的图像，如果您查看注释行，您可以看到根URL+图像剩余的URL。我需要在UI上显示该图像（不是GIF唯一图像），示例图像URL:@ SReijthsRe得到它，您修改了 CyyCopyVIEVIEVCELL .Cs<代码>文件添加方法以显示URL图像。然后它将显示。我已经通过用% 20替换空白空间来解决这个问题，现在我可以在UI上查看我的图像。非常感谢。