Xamarin.forms中的共享首选项 [英] Shared Preferences in Xamarin.forms

问题描述

如果用户使用

Application.Current.Properties["isLoggedIn"] = "true";

，但不起作用.如果我从后台删除我的应用程序，它将再次显示登录页面，但是如果用户已登录，则应显示下一页.

but its not working. If i remove my app from background it again shows the login page but if user is logged in it should show the next page.

推荐答案

在使用应用程序属性字典"时，您需要牢记以下几点:

When using 'Application Properties Dictionary' you have to keep in mind few things:

• 根据官方文档:属性字典会自动保存到设备中".但是，如果要确保持久性，则必须显式调用SavePropertiesAsync().
• 属性"字典只能序列化基本类型以进行存储.尝试存储其他类型(例如List)可能会失败，并且会自动失败.

阅读官方文档仔细并注意细节.

这是一个代码示例:

Read the official documentation carefully and pay attention to details.

Here is a code example:

private async Task SaveApplicationProperty<T>(string key, T value)
{
    Xamarin.Forms.Application.Current.Properties[key] = value;
    await Xamarin.Forms.Application.Current.SavePropertiesAsync();
}

private T LoadApplicationProperty<T>(string key)
{
    return (T) Xamarin.Forms.Application.Current.Properties[key];
}

// To save your property
await SaveApplicationProperty("isLoggedIn", true);

// To load your property
bool isLoggedIn = LoadApplicationProperty<bool>("isLoggedIn");

根据您的需求，您可以考虑本地数据库或设置插件代替.但是，只保存一些原始值，Application Properties方法就足够了.

Base on your needs you may consider Local Database or Settings Plugin instead. However for saving just a few primitive values Application Properties approach should be good enough.

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