PSListController extension to load JSON files.

PSListController+JSON.h

#include <Preferences/PSListController.h>

@interface PSListController (JSON)

- (NSMutableArray *)loadSpecifiersFromJSONName:(NSString *)name target:(PSListController *)target;
- (NSMutableArray *)loadSpecifiersFromJSONName:(NSString *)name target:(PSListController *)target bundle:(NSBundle *)bundle;

@end

PSListController+JSON.m

#include "PSListController+JSON.h"
#include <dlfcn.h>

typedef NSArray *(*SpecifiersFromPlistType)(NSDictionary *plist, PSSpecifier *prevSpec, id target, NSString *plistName, NSBundle *curBundle, NSString **pTitle, NSString **pSpecifierID, PSListController *controller, NSMutableArray **pBundleControllers);
static SpecifiersFromPlistType SpecifiersFromPlist;

@implementation PSListController (JSON)
- (NSMutableArray *)loadSpecifiersFromJSONName:(NSString *)name target:(PSListController *)target {
    return [self loadSpecifiersFromJSONName:name target:target bundle:[NSBundle bundleForClass:[target class]]];
}

- (NSMutableArray *)loadSpecifiersFromJSONName:(NSString *)name target:(PSListController *)target bundle:(NSBundle *)bundle {
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        void *preferences = dlopen("/System/Library/PrivateFrameworks/Preferences.framework/Preferences", RTLD_LAZY);
        SpecifiersFromPlist = (SpecifiersFromPlistType)dlsym(preferences, "SpecifiersFromPlist");
    });

    NSString *path = [bundle pathForResource:name ofType:@"json"];
    if (!path) {
        NSLog(@"Warning: failed to load preference json '%@.json' for bundle %@", name, bundle);
    }

    NSData *data = [NSData dataWithContentsOfFile:path];
    NSError *error = nil;
    NSDictionary *json = [NSJSONSerialization JSONObjectWithData:data options:0 error:&error];
    if (error) {
        NSLog(@"Error: failed to parse preference json '%@.json' for bundle %@: %@", name, bundle, error);
        return nil;
    }

    NSString *specifierID;
    NSString *_title;
    NSArray *bundleControllers = [self valueForKey:@"_bundleControllers"];

    NSArray *result = SpecifiersFromPlist(json, self->_specifier, target, name, bundle,
                                          &_title, &specifierID, self, &bundleControllers);

    self.specifierID = specifierID;
    self.title = _title;

    return [result mutableCopy];
}

@end

Root.json

{
    "items": [
        {
            "cell": "PSGroupCell",
            "label": "JSON Test First Page"
        },
        {
            "cell": "PSSwitchCell",
            "default": true,
            "defaults": "com.yourcompany.jsontest",
            "key": "AwesomeSwitch1",
            "label": "Awesome Switch 1"
        }
    ],
    "title": "JSON Test"
}