Access load status

View inAndroidFormsUWPWPFWinUIiOSView on GitHub

Determine the map's load status which can be: NotLoaded, FailedToLoad, Loading, Loaded.

screenshot

Use case

Knowing the map's load state may be required before subsequent actions can be executed.

How to use the sample

The load status of the map will be displayed as the sample loads.

How it works

  1. Create a Map and add it to a MapView.
  2. Use the Map.LoadStatusChanged event to listen for changes in the map's load status.

The LoadStatus is Loaded when any of the following criteria are met:

  • The map has a valid spatial reference.
  • The map has an an initial viewpoint.
  • One of the map's predefined layers has been created.

Relevant API

  • Map
  • ILoadable
  • MapView

Tags

LoadStatus, Loadable pattern, Map

Sample Code

AccessLoadStatus.cs
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// Copyright 2016 Esri.
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License.
// You may obtain a copy of the License at: http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific
// language governing permissions and limitations under the License.

using Esri.ArcGISRuntime;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.UI.Controls;
using Foundation;
using UIKit;

namespace ArcGISRuntime.Samples.AccessLoadStatus
{
    [Register("AccessLoadStatus")]
    [ArcGISRuntime.Samples.Shared.Attributes.Sample(
        name: "Access load status",
        category: "Map",
        description: "Determine the map's load status which can be: `NotLoaded`, `FailedToLoad`, `Loading`, `Loaded`.",
        instructions: "The load status of the map will be displayed as the sample loads.",
        tags: new[] { "LoadStatus", "Loadable pattern", "Map" })]
    public class AccessLoadStatus : UIViewController
    {
        // Hold references to UI controls.
        private MapView _myMapView;
        private UILabel _loadStatusLabel;

        public AccessLoadStatus()
        {
            Title = "Access load status";
        }

        private void OnMapsLoadStatusChanged(object sender, LoadStatusEventArgs e)
        {
            // Make sure that the UI changes are done in the UI thread.
            InvokeOnMainThread(() =>
            {
                // Update the load status information.
                _loadStatusLabel.Text = $"Map's load status: {e.Status}";
            });
        }

        public override void LoadView()
        {
            // Create the views.
            View = new UIView() { BackgroundColor = ApplicationTheme.BackgroundColor };

            _myMapView = new MapView();
            _myMapView.TranslatesAutoresizingMaskIntoConstraints = false;

            _loadStatusLabel = new UILabel
            {
                BackgroundColor = UIColor.FromWhiteAlpha(0f, .6f),
                TextColor = UIColor.White,
                TextAlignment = UITextAlignment.Center,
                TranslatesAutoresizingMaskIntoConstraints = false
            };

            // Add the views.
            View.AddSubviews(_myMapView, _loadStatusLabel);

            // Lay out the views.
            NSLayoutConstraint.ActivateConstraints(new[]
            {
                _myMapView.LeadingAnchor.ConstraintEqualTo(View.LeadingAnchor),
                _myMapView.TrailingAnchor.ConstraintEqualTo(View.TrailingAnchor),
                _myMapView.TopAnchor.ConstraintEqualTo(View.TopAnchor),
                _myMapView.BottomAnchor.ConstraintEqualTo(View.BottomAnchor),

                _loadStatusLabel.TopAnchor.ConstraintEqualTo(View.SafeAreaLayoutGuide.TopAnchor),
                _loadStatusLabel.TrailingAnchor.ConstraintEqualTo(View.TrailingAnchor),
                _loadStatusLabel.LeadingAnchor.ConstraintEqualTo(View.LeadingAnchor),
                _loadStatusLabel.HeightAnchor.ConstraintEqualTo(40)
            });
        }

        public override void ViewWillAppear(bool animated)
        {
            base.ViewWillAppear(animated);

            // Create new Map with basemap.
            Map myMap = new Map(BasemapStyle.ArcGISImageryStandard);

            // Register to handle loading status changes.
            myMap.LoadStatusChanged += OnMapsLoadStatusChanged;

            // Show the map.
            _myMapView.Map = myMap;
        }

        public override void ViewDidDisappear(bool animated)
        {
            base.ViewDidDisappear(animated);

            // Unsubscribe from events, per best practice.
            _myMapView.Map.LoadStatusChanged -= OnMapsLoadStatusChanged;
        }
    }
}

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