/*

 Copyright (C) 2014 Apple Inc. All Rights Reserved.

 See LICENSE.txt for this sample’s licensing information

 Abstract:

  The application' delegate.  Handles loading and registering the default values

  for each setting from the Settings bundle.

 */

#import "AppPrefsAppDelegate.h"

@implementation AppPrefsAppDelegate

//| ----------------------------------------------------------------------------

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions

{

    // The registration domain is volatile.  It does not persist across launches.

    // You must register your defaults at each launch; otherwise you will get

    // (system) default values when accessing the values of preferences the

    // user (via the Settings app) or your app (via set*:forKey:) has not

    // modified.  Registering a set of default values ensures that your app

    // always has a known good set of values to operate on.

    [self populateRegistrationDomain];

    return YES;

}

//| ----------------------------------------------------------------------------

//! Locates the file representing the root page of the settings for this app,

//! invokes loadDefaults:fromSettingsPage:inSettingsBundleAtURL: on it,

//! and registers the loaded values as the app's defaults.

//

- (void)populateRegistrationDomain

{

    NSURL *settingsBundleURL = [[NSBundle mainBundle] URLForResource:@"Settings" withExtension:@"bundle"];

    // Invoke loadDefaultsFromSettingsPage:inSettingsBundleAtURL: on the property

    // list file for the root settings page (always named Root.plist).

    NSDictionary *appDefaults = [self loadDefaultsFromSettingsPage:@"Root.plist" inSettingsBundleAtURL:settingsBundleURL];

    // appDefaults is now populated with the preferences and their default values.

    // Add these to the registration domain.

    [[NSUserDefaults standardUserDefaults] registerDefaults:appDefaults];

    [[NSUserDefaults standardUserDefaults] synchronize];

}

//| ----------------------------------------------------------------------------

//! Helper function that parses a Settings page file, extracts each preference

//! defined within along with its default value.  If the page contains a

//! 'Child Pane Element', this method will recurs on the referenced page file.

//

- (NSDictionary*)loadDefaultsFromSettingsPage:(NSString*)plistName inSettingsBundleAtURL:(NSURL*)settingsBundleURL

{

    // Each page of settings is represented by a property-list file that follows

    // the Settings Application Schema:

    // <https://developer.apple.com/library/ios/#documentation/PreferenceSettings/Conceptual/SettingsApplicationSchemaReference/Introduction/Introduction.html>.

    // Create an NSDictionary from the plist file.

    NSDictionary *settingsDict = [NSDictionary dictionaryWithContentsOfURL:[settingsBundleURL URLByAppendingPathComponent:plistName]];

    // The elements defined in a settings page are contained within an array

    // that is associated with the root-level PreferenceSpecifiers key.

    NSArray *prefSpecifierArray = settingsDict[@"PreferenceSpecifiers"];

    // If prefSpecifierArray is nil, something wen't wrong.  Either the

    // specified plist does ot exist or is malformed.

    if (prefSpecifierArray == nil)

        return nil;

    // Create a dictionary to hold the parsed results.

    NSMutableDictionary *keyValuePairs = [NSMutableDictionary dictionary];

    for (NSDictionary *prefItem in prefSpecifierArray)

    // Each element is itself a dictionary.

    {

        // What kind of control is used to represent the preference element in the

        // Settings app.

        NSString *prefItemType = prefItem[@"Type"];

        // How this preference element maps to the defaults database for the app.

        NSString *prefItemKey = prefItem[@"Key"];

        // The default value for the preference key.

        NSString *prefItemDefaultValue = prefItem[@"DefaultValue"];

        if ([prefItemType isEqualToString:@"PSChildPaneSpecifier"])

        // If this is a 'Child Pane Element'.  That is, a reference to another

        // page.

        {

            // There must be a value associated with the 'File' key in this preference

            // element's dictionary.  Its value is the name of the plist file in the

            // Settings bundle for the referenced page.

            NSString *prefItemFile = prefItem[@"File"];

            // Recurs on the referenced page.

            NSDictionary *childPageKeyValuePairs = [self loadDefaultsFromSettingsPage:prefItemFile inSettingsBundleAtURL:settingsBundleURL];

            // Add the results to our dictionary

            [keyValuePairs addEntriesFromDictionary:childPageKeyValuePairs];

        }

        else if (prefItemKey != nil && prefItemDefaultValue != nil)

        // Some elements, such as 'Group' or 'Text Field' elements do not contain

        // a key and default value.  Skip those.

        {

            keyValuePairs[prefItemKey] = prefItemDefaultValue;

        }

    }

    return keyValuePairs;

}

@end