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Helper preferences

Trevor DeVore edited this page Jul 30, 2019 · 15 revisions

Levure provides your LiveCode application with a preferences management system.

On macOS an extension (>= LC 9) or an external (< LC 9) is used so you can set preferences using the macOS NSUserDefaults API. On iOS an extension is used to access NSUserDefaults. On Windows, Linux, and Android preferences are stored in a file containing data serialized using arrayEncode.

Contents

Activate the preferences framework helper

The levure/framework/helpers/preferences helper provides an API for managing your application preferences. By default this helper is activated for you in app.yml:

# app.yml

helpers:
  - folder: ./helpers
  - filename: "[[FRAMEWORK]]/helpers/preferences"

Set the preferences file name

You set the preferences file name for the platforms your application supports in app.yml. You can provide an optional default file name for all platforms and then override it for specific platforms. A file name can be specified for user which is for the the current user using the application, or for shared which is shared among all users on the computer. Note the shared is only available on macOS, windows, and linux. It is not supported on mobile devices.

The "user" preferences file is stored in the folder returned by levureApplicationDataFolder("user") on all platforms except macOS, where it is stored in ~/Library/Preferences, so you should specify only the name of the preferences file without any other path information.

The "shared" preferences file is stored in the folder returned by levureApplicationDataFolder("shared") on all supported platforms.

Do not use quote marks around your preferences filename value in app.yml.

# app.yml

preferences filename:
  user:
    default:
    macos:
    windows:
    linux:
    ios:
    android:
  shared:
    default:
    macos:
    windows:
    linux:

Examples

You can set an optional default preferences filename for all platforms and then override it for specific platforms. So this:

preferences filename:
  user:
    default: My Application.prefs
    macos: com.mycompany.myapplication
    windows:
    linux:
    ios: com.mycompany.myapplication
    android:

Will cause your application to create and use these user preferences file names:

Platform Preferences File Name
macOS com.mycompany.myapplication
Windows My Application.prefs
Linux My Application.prefs
iOS com.mycompany.myapplication
Android My Application.prefs

Note that in this example the default: preferences file name is used for all platforms except for macOS and iOS where it is overridden with the macos: and ios: file names.

Set default preferences values

You can set default preferences values in a prefs.yml file that sits alongside app.yml in your app folder. You specify the default values by entering them as name: value pairs, one preference per line.

Do not use quote marks around your default preferences values in prefs.yml.

# prefs.yml

my preference 1: my preference 1 default value
my preference 2: 100
my preference 3: true

Packaging prefs.yml

If you create a prefs.yml file then remember to include it when packaging your application. This is done by adding prefs.yml to the copy files section. Here is an example:


build profiles:
  all profiles:
    copy files:
      all platforms:
        - filename: prefs.yml

Set a preference to a value

While your application is running you can set an application preference to a value with the prefsSetPref command. If the preference does not already exist, it will be created and set to the value.

# prefsSetPref examples
prefsSetPref "my preference 1", "a string value"
prefsSetPref "my preference 2", 80
prefsSetPref "my preference 3", false

Get a preference value

While your application is running you can get a preference value with the prefsGetPref function.

# prefsGetPref example
put prefsGetPref("my preference name") into tPreferenceValue

Saving preferences

Levure will automatically call prefsSave when your application is running as a standalone and shuts down. prefsSave "user" and prefsSave "shared" is called in the levureShutdownApplication command in the levure.livecodescript script. You can save preferences at any other point by calling prefsSave user|shared.


API


prefsGetDefaults

Type: function

Syntax: prefsGetDefaults(<pUserOrShared>)

Summary: Returns the entire array of default preferences.

Returns: Array representing YAML configuration store in prefs.yml and prefs_shared.yml

Parameters:

Name Description
pUserOrShared Preferences category. "user" or "shared". Default is "user".

prefsGetPref

Type: function

Syntax: prefsGetPref(<pKey>,<pUserOrShared>)

Summary: Gets an application preference.

Returns: value

Parameters:

Name Description
pKey Name of preference to get.
pUserOrShared Preferences category. "user" or "shared". Default is "user".

prefsGetPreferenceFile

Type: function

Syntax: prefsGetPreferenceFile(<pUserOrShared>)

Summary: Returns the file where preferences are stored.

Returns: Filename or empty

Parameters:

Name Description
pUserOrShared Preferences category. "user" or "shared". Default is "user".

Description:

Returns the filename of the preference file.


prefsIsCategoryConfigured

Type: function

Syntax: prefsIsCategoryConfigured(<pUserOrShared>)

Summary: Use this to check if preferences have been configured for "user" or "shared".

Returns: Boolean


prefsIsPrefSet

Type: function

Syntax: prefsIsPrefSet(<pKey>,<pUserOrShared>)

Summary: Checks if a preference has been set on the computer the application is running on.

Returns: true/false

Parameters:

Name Description
pKey Name of preference to check.
pUserOrShared Preferences category. "user" or "shared". Default is "user".

prefsReload

Type: command

Syntax: prefsReload <pUserOrShared>

Summary: Reloads preferences from the file on disk.

Returns: Empty

Parameters:

Name Description
pUserOrShared Preferences category. "user" or "shared". Default is "user".

Description:

This handler will clear out any values that are stored internally and reloads preferences from the file on disk.

Note that this command does nothing on macOS or iOS which handle preferences using the NSUserDefaults APIs.


prefsReset

Type: command

Syntax: prefsReset <pUserOrShared>

Summary: Resets all values in in preferences to empty.

Returns: Empty

Parameters:

Name Description
pUserOrShared Preferences category. "user" or "shared". Default is "user".

Description:

Use this handler if you would like to reset all preferences to their default values as defined in prefs.yml and prefs_shared.yml.

Note that on macOS this command currently does not work.


prefsSave

Type: command

Syntax: prefsSave <pUserOrShared>

Summary: Saves preferences to disk.

Returns: Error message

Parameters:

Name Description
pUserOrShared Preferences category. "user" or "shared". Default is "user".

Description:

When setting preferences the preference is updated in memory. To permanently store changes on disk use this command.


prefsSetPref

Type: command

Syntax: prefsSetPref <pKey>,<pValue>,<pUserOrShared>,<pType>

Summary: Sets an application preference.

Returns: error message

Parameters:

Name Description
pKey Name of preference to set.
pValue Value to set preference to. This can be a string or an array.
pUserOrShared Preferences category. "user" or "shared". Default is "user".
pType Pass in "binary" to force pref to be stored as binary (macOS and iOS). By default if value contains NULL then it will be stored as binary.
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