How does the preference Preferences in XamarinEssentials determine whether a project exists
Xiaobian to share with you XamarinEssentials Preferences Preferences how to determine whether the project exists, I hope you have read this article after the harvest, let us discuss it together!
Preferences can also be referred to as preferences. It stores data in the form of key-value pairs and is suitable for storing small amounts of user data. For example, after saving a user's personalized settings, the settings can be loaded every time the application is opened to enhance the user's experience. Even after you uninstall an app, you can keep your data for the next time you install it. The Xamarin.Essentials component provides a static Preferences class for managing preference data.
Determine whether the project exists
When operating on a preference item, you first need to determine whether the item exists. In this case, you need to use the ContainsKey() method of the Preferences class. This method comes in two forms, described in turn below.
(1) The syntax of ContainsKey(string) method is as follows:
public static bool ContainsKey(string key)
where the key parameter specifies the key for the preference.
(2) The syntax of ContainsKey(string, string) method is as follows:
public static bool ContainsKey(string key, string sharedName)
where the key parameter specifies the key for the preference and the sharedName parameter specifies the shared container name.
Note: Both methods return Boolean values. When the return value is true, the specified key exists; otherwise, it does not.
Example 1-4: The following will determine whether the specified key exists in the preferences. The code is as follows:
void Preferences_ContainsKey(string key)
{
//determine whether the specified key exists
if (Preferences.ContainsKey(key))
{
//The specified key exists
Console.WriteLine("The specified key exists");
}
else
{
//The specified key does not exist
Console.WriteLine("The specified key does not exist");
}
}
Run the program, if the specified key exists, will output the following content:
The specified key exists
If the specified key does not exist, the following is output:
The specified key does not exist
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