将版本跟踪数据从 Xamarin.Forms 应用迁移到 .NET MAUI 应用

项目
05/14/2024

Xamarin.Essentials 和 .NET Multi-platform App UI (.NET MAUI) 都包含 VersionTracking 类，可用于检查应用的版本和内部版本号，以及是否是首次发布应用等其他信息。但是，在 Xamarin.Essentials 中，版本跟踪数据存储在名称为 {your-app-package-id}.xamarinessentials.versiontracking 的特定于平台的首选项容器中，而在 .NET MAUI 中，版本跟踪数据存储在名称为 {your-app-package-id}.microsoft.maui.essentials.versiontracking 的特定于平台的首选项容器中。

将使用 VersionTracking 类的 Xamarin.Forms 应用迁移到 .NET MAUI 时，必须处理此首选项容器命名差异，以便为用户提供流畅的升级体验。本文介绍如何使用 LegacyVersionTracking 类和帮助程序类来处理首选项容器。 LegacyVersionTracking 类支持 Android、iOS 和 Windows 上的 .NET MAUI 应用读取使用早先版本的 Xamarin.Forms 应用创建的版本跟踪数据。

重要

为了使 LegacyVersionTracking 类正常工作，.NET MAUI 应用的版本号必须高于 Xamarin.Forms 应用的版本号。可以使用 $(ApplicationVersion) 和 $(ApplicationDisplayVersion) 生成属性在 .NET MAUI 应用的项目文件中设置版本号。

有关 Xamarin.Essentials 中 VersionTracking 类的详细信息，请参阅 Xamarin.Essentials：版本跟踪。有关 .NET MAUI 中 VersionTracking 类的详细信息，请参阅版本跟踪。

访问旧版版本跟踪数据

以下代码展示了 LegacyVersionTracking 类，可通过该类访问 Xamarin.Forms 应用创建的版本跟踪数据。

注意

要使用此代码，请将其添加到 .NET MAUI 应用项目中名为 LegacyVersionTracking 的类。

namespace MigrationHelpers;

public static class LegacyVersionTracking
{
    const string versionsKey = "VersionTracking.Versions";
    const string buildsKey = "VersionTracking.Builds";

    static readonly string sharedName = LegacyPreferences.GetPrivatePreferencesSharedName("versiontracking");

    static Dictionary<string, List<string>> versionTrail;
    static string LastInstalledVersion => versionTrail[versionsKey].LastOrDefault();
    static string LastInstalledBuild => versionTrail[buildsKey].LastOrDefault();

    public static string VersionsKey => versionsKey;
    public static string BuildsKey => buildsKey;
    public static string SharedName => sharedName;
    public static bool IsFirstLaunchEver { get; private set; }
    public static bool IsFirstLaunchForCurrentVersion { get; private set; }
    public static bool IsFirstLaunchForCurrentBuild { get; private set; }
    public static string CurrentVersion => AppInfo.VersionString;
    public static string CurrentBuild => AppInfo.BuildString;
    public static string PreviousVersion => GetPrevious(versionsKey);
    public static string PreviousBuild => GetPrevious(buildsKey);
    public static string FirstInstalledVersion => versionTrail[versionsKey].FirstOrDefault();
    public static string FirstInstalledBuild => versionTrail[buildsKey].FirstOrDefault();
    public static IEnumerable<string> VersionHistory => versionTrail[versionsKey].ToArray();
    public static IEnumerable<string> BuildHistory => versionTrail[buildsKey].ToArray();
    public static bool IsFirstLaunchForVersion(string version) => CurrentVersion == version && IsFirstLaunchForCurrentVersion;
    public static bool IsFirstLaunchForBuild(string build) => CurrentBuild == build && IsFirstLaunchForCurrentBuild;

    static LegacyVersionTracking()
    {
        InitVersionTracking();
    }

    internal static void InitVersionTracking()
    {
        IsFirstLaunchEver = !LegacyPreferences.ContainsKey(versionsKey, sharedName) || !LegacyPreferences.ContainsKey(buildsKey, sharedName);
        if (IsFirstLaunchEver)
        {
            versionTrail = new Dictionary<string, List<string>>
                {
                    { versionsKey, new List<string>() },
                    { buildsKey, new List<string>() }
                };
        }
        else
        {
            versionTrail = new Dictionary<string, List<string>>
                {
                    { versionsKey, ReadHistory(versionsKey).ToList() },
                    { buildsKey, ReadHistory(buildsKey).ToList() }
                };
        }

        IsFirstLaunchForCurrentVersion = !versionTrail[versionsKey].Contains(CurrentVersion) || CurrentVersion != LastInstalledVersion;
        if (IsFirstLaunchForCurrentVersion)
        {
            // Avoid duplicates and move current version to end of list if already present
            versionTrail[versionsKey].RemoveAll(v => v == CurrentVersion);
            versionTrail[versionsKey].Add(CurrentVersion);
        }

        IsFirstLaunchForCurrentBuild = !versionTrail[buildsKey].Contains(CurrentBuild) || CurrentBuild != LastInstalledBuild;
        if (IsFirstLaunchForCurrentBuild)
        {
            // Avoid duplicates and move current build to end of list if already present
            versionTrail[buildsKey].RemoveAll(b => b == CurrentBuild);
            versionTrail[buildsKey].Add(CurrentBuild);
        }
    }

    static string GetPrevious(string key)
    {
        var trail = versionTrail[key];
        return (trail.Count >= 2) ? trail[trail.Count - 2] : null;
    }

    static string[] ReadHistory(string key) => LegacyPreferences.Get(key, null, sharedName)?.Split(new[] { '|' }, StringSplitOptions.RemoveEmptyEntries) ?? new string[0];
}

LegacyVersionTracking 类使用 LegacyPreferences 类，可通过该类访问 Xamarin.Forms 应用中的 Xamarin.Essentials Preferences 类存储的版本跟踪数据：

注意

要使用此代码，请将其添加到 .NET MAUI 应用项目中名为 LegacyPreferences 的类。

#if ANDROID || IOS || WINDOWS
namespace MigrationHelpers;

public static partial class LegacyPreferences
{
    internal static string GetPrivatePreferencesSharedName(string feature) => $"{AppInfo.PackageName}.xamarinessentials.{feature}";

    public static bool ContainsKey(string key, string sharedName) => PlatformContainsKey(key, sharedName);
    public static void Remove(string key, string sharedName) => PlatformRemove(key, sharedName);
    public static string Get(string key, string defaultValue, string sharedName) => PlatformGet<string>(key, defaultValue, sharedName);
}
#endif

LegacyPreferences 类是一个 partial 类，其剩余实现是特定于平台的。

Android

在 Android 上，LegacyPreferences 类提供了从共享首选项检索数据的首选项容器实现。以下代码显示 LegacyPreferences 类：

注意

要使用此代码，请将其添加到 .NET MAUI 应用项目的 Platforms\Android 文件夹中名为 LegacyPreferences 的类。

using System.Globalization;
using Android.Content;
using Android.Preferences;
using Application = Android.App.Application;

namespace MigrationHelpers;

public static partial class LegacyPreferences
{
    static readonly object locker = new object();

    static bool PlatformContainsKey(string key, string sharedName)
    {
        lock (locker)
        {
            using (var sharedPreferences = GetSharedPreferences(sharedName))
            {
                return sharedPreferences.Contains(key);
            }
        }
    }

    static void PlatformRemove(string key, string sharedName)
    {
        lock (locker)
        {
            using (var sharedPreferences = GetSharedPreferences(sharedName))
            using (var editor = sharedPreferences.Edit())
            {
                editor.Remove(key).Apply();
            }
        }
    }

    static T PlatformGet<T>(string key, T defaultValue, string sharedName)
    {
        lock (locker)
        {
            object value = null;
            using (var sharedPreferences = GetSharedPreferences(sharedName))
            {
                if (defaultValue == null)
                {
                    value = sharedPreferences.GetString(key, null);
                }
                else
                {
                    switch (defaultValue)
                    {
                        case int i:
                            value = sharedPreferences.GetInt(key, i);
                            break;
                        case bool b:
                            value = sharedPreferences.GetBoolean(key, b);
                            break;
                        case long l:
                            value = sharedPreferences.GetLong(key, l);
                            break;
                        case double d:
                            var savedDouble = sharedPreferences.GetString(key, null);
                            if (string.IsNullOrWhiteSpace(savedDouble))
                            {
                                value = defaultValue;
                            }
                            else
                            {
                                if (!double.TryParse(savedDouble, NumberStyles.Number | NumberStyles.AllowExponent, CultureInfo.InvariantCulture, out var outDouble))
                                {
                                    var maxString = Convert.ToString(double.MaxValue, CultureInfo.InvariantCulture);
                                    outDouble = savedDouble.Equals(maxString) ? double.MaxValue : double.MinValue;
                                }

                                value = outDouble;
                            }
                            break;
                        case float f:
                            value = sharedPreferences.GetFloat(key, f);
                            break;
                        case string s:
                            // the case when the string is not null
                            value = sharedPreferences.GetString(key, s);
                            break;
                    }
                }
            }

            return (T)value;
        }
    }

    static ISharedPreferences GetSharedPreferences(string sharedName)
    {
        var context = Application.Context;

        return string.IsNullOrWhiteSpace(sharedName) ?
#pragma warning disable CS0618 // Type or member is obsolete
            PreferenceManager.GetDefaultSharedPreferences(context) :
#pragma warning restore CS0618 // Type or member is obsolete
                context.GetSharedPreferences(sharedName, FileCreationMode.Private);
    }
}

iOS

在 iOS 上，LegacyPreferences 类提供了从 NSUserDefaults 中检索数据的首选项容器实现。以下代码显示 LegacyPreferences 类：

注意

要使用此代码，请将其添加到 .NET MAUI 应用项目的 Platforms\iOS 文件夹中名为 LegacyPreferences 的类。

using Foundation;
using System.Globalization;

namespace MigrationHelpers;

public static partial class LegacyPreferences
{
    static readonly object locker = new object();

    static bool PlatformContainsKey(string key, string sharedName)
    {
        lock (locker)
        {
            return GetUserDefaults(sharedName)[key] != null;
        }
    }

    static void PlatformRemove(string key, string sharedName)
    {
        lock (locker)
        {
            using (var userDefaults = GetUserDefaults(sharedName))
            {
                if (userDefaults[key] != null)
                    userDefaults.RemoveObject(key);
            }
        }
    }

    static T PlatformGet<T>(string key, T defaultValue, string sharedName)
    {
        object value = null;

        lock (locker)
        {
            using (var userDefaults = GetUserDefaults(sharedName))
            {
                if (userDefaults[key] == null)
                    return defaultValue;

                switch (defaultValue)
                {
                    case int i:
                        value = (int)(nint)userDefaults.IntForKey(key);
                        break;
                    case bool b:
                        value = userDefaults.BoolForKey(key);
                        break;
                    case long l:
                        var savedLong = userDefaults.StringForKey(key);
                        value = Convert.ToInt64(savedLong, CultureInfo.InvariantCulture);
                        break;
                    case double d:
                        value = userDefaults.DoubleForKey(key);
                        break;
                    case float f:
                        value = userDefaults.FloatForKey(key);
                        break;
                    case string s:
                        // the case when the string is not null
                        value = userDefaults.StringForKey(key);
                        break;
                    default:
                        // the case when the string is null
                        if (typeof(T) == typeof(string))
                            value = userDefaults.StringForKey(key);
                        break;
                }
            }
        }

        return (T)value;
    }

    static NSUserDefaults GetUserDefaults(string sharedName)
    {
        if (!string.IsNullOrWhiteSpace(sharedName))
            return new NSUserDefaults(sharedName, NSUserDefaultsType.SuiteName);
        else
            return NSUserDefaults.StandardUserDefaults;
    }
}

Windows

在 Windows 上，LegacyVersionTracking 类提供了从 ApplicationDataContainer 中检索数据的首选项容器实现。以下代码显示 LegacyPreferences 类：

注意

要使用此代码，请将其添加到 .NET MAUI 应用项目 Platforms\Windows 文件夹中名为 LegacyPreferences 的类。

using Windows.Storage;

namespace MigrationHelpers;

public static partial class LegacyPreferences
{
    static readonly object locker = new object();

    static bool PlatformContainsKey(string key, string sharedName)
    {
        lock (locker)
        {
            var appDataContainer = GetApplicationDataContainer(sharedName);
            return appDataContainer.Values.ContainsKey(key);
        }
    }

    static void PlatformRemove(string key, string sharedName)
    {
        lock (locker)
        {
            var appDataContainer = GetApplicationDataContainer(sharedName);
            if (appDataContainer.Values.ContainsKey(key))
                appDataContainer.Values.Remove(key);
        }
    }

    static T PlatformGet<T>(string key, T defaultValue, string sharedName)
    {
        lock (locker)
        {
            var appDataContainer = GetApplicationDataContainer(sharedName);
            if (appDataContainer.Values.ContainsKey(key))
            {
                var tempValue = appDataContainer.Values[key];
                if (tempValue != null)
                    return (T)tempValue;
            }
        }

        return defaultValue;
    }

    static ApplicationDataContainer GetApplicationDataContainer(string sharedName)
    {
        var localSettings = ApplicationData.Current.LocalSettings;
        if (string.IsNullOrWhiteSpace(sharedName))
            return localSettings;

        if (!localSettings.Containers.ContainsKey(sharedName))
            localSettings.CreateContainer(sharedName, ApplicationDataCreateDisposition.Always);

        return localSettings.Containers[sharedName];
    }
}

使用旧版本跟踪数据

LegacyVersionTracking 类可用于检索使用早先版本的 Xamarin.Forms 应用在 Android、iOS 和 Windows 上创建的版本跟踪数据：

#if ANDROID || IOS || WINDOWS
using MigrationHelpers;
...

string isFirstLaunchEver = LegacyVersionTracking.IsFirstLaunchEver.ToString();
string currentVersionIsFirst = LegacyVersionTracking.IsFirstLaunchForCurrentVersion.ToString();
string currentBuildIsFirst = LegacyVersionTracking.IsFirstLaunchForCurrentBuild.ToString();
string currentVersion = LegacyVersionTracking.CurrentVersion.ToString();
string currentBuild = LegacyVersionTracking.CurrentBuild.ToString();
string firstInstalledVer = LegacyVersionTracking.FirstInstalledVersion.ToString();
string firstInstalledBuild = LegacyVersionTracking.FirstInstalledBuild.ToString();
string versionHistory = String.Join(',', LegacyVersionTracking.VersionHistory);
string buildHistory = String.Join(',', LegacyVersionTracking.BuildHistory);
string previousVersion = LegacyVersionTracking.PreviousVersion?.ToString() ?? "none";
string previousBuild = LegacyVersionTracking.PreviousBuild?.ToString() ?? "none";
#endif

此示例展示了如何使用 LegacyVersionTracking 类读取旧版跟踪数据。但是，无法将此数据分配给 .NET MAUI 的 VersionTracking 类，因为无法设置其属性。不过，可以使用 WriteHistory 方法将数据写入 .NET MAUI 首选项：

void WriteHistory(string key, IEnumerable<string> history)
{
    Preferences.Default.Set(key, string.Join("|", history), $"{AppInfo.Current.PackageName}.microsoft.maui.essentials.versiontracking");
}

#if ANDROID || IOS || WINDOWS
WriteHistory(LegacyVersionTracking.VersionsKey, LegacyVersionTracking.VersionHistory);
WriteHistory(LegacyVersionTracking.BuildsKey, LegacyVersionTracking.BuildHistory);
#endif

将旧版跟踪数据写入到 .NET MAUI 首选项后，.NET MAUI 的 VersionTracking 类就可以使用这些数据：

var mauiVersionHistory = VersionTracking.Default.VersionHistory;
var mauiBuildHistory = VersionTracking.Default.BuildHistory;

然后，可以从设备中删除旧版跟踪数据：

#if ANDROID || IOS || WINDOWS
LegacyPreferences.Remove(LegacyVersionTracking.VersionsKey, LegacyVersionTracking.SharedName);
LegacyPreferences.Remove(LegacyVersionTracking.BuildsKey, LegacyVersionTracking.SharedName);
#endif

通过

将版本跟踪数据从 Xamarin.Forms 应用迁移到 .NET MAUI 应用

访问旧版版本跟踪数据

Android

iOS

Windows

使用旧版本跟踪数据

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