Encryption is a decent method of scrambling the data but i don't know how to implement encription concept.

NSString *filePath = [[NSBundle mainBundle] pathForResource:@"Data" ofType:@"plist"];
    NSArray *arrData = [[NSArray alloc]initWithContentsOfFile:filePath];

    NSData *datas = [NSKeyedArchiver archivedDataWithRootObject:arrData];
    [datas writeToFile:filePath atomically:YES];

@implementation TestViewController

- (void)viewDidLoad
{
    [super viewDidLoad];

    NSString *path = [[NSBundle mainBundle] pathForResource:@"Encryption-Test" ofType:@"enc"];
    NSData *passEncryptedData =[[NSData alloc] initWithContentsOfFile:path];
    NSString *pass = @"asdasd";

    NSData *dataDecrypted = [RNOpenSSLDecryptor decryptData:passEncryptedData withSettings:kRNCryptorAES256Settings password:pass error:nil];
    id plist = [NSPropertyListSerialization propertyListFromData:dataDecrypted mutabilityOption:NSPropertyListImmutable format:nil errorDescription:nil];

    assert(plist);
    self.text.text = [plist description];
}

@end

NSString *txtPath = [documentsDirectory stringByAppendingPathComponent:@"questions.enc"];

    if ([fileManager fileExistsAtPath:txtPath] == NO) {
        NSString *resourcePath = [[NSBundle mainBundle] pathForResource:@"questions" ofType:@"enc"];
        [fileManager copyItemAtPath:resourcePath toPath:txtPath error:&error];
    }

    NSString *filePath1 = [documentsDirectory stringByAppendingPathComponent:@"questions.encr"];

    NSData *passEncryptedData =[[NSData alloc] initWithContentsOfFile:filePath1]  ;
    NSString *pass = @"asdf"; // Insert your password from step 1

    NSData *dataDecrypted = [RNOpenSSLDecryptor decryptData:passEncryptedData withSettings:kRNCryptorAES256Settings password:pass error:&error];

        NSString *appFile = [documentsDirectory stringByAppendingPathComponent:@"questionsDECRYPTED.plist"]; //The Decrypted file saved here
        [dataDecrypted writeToFile:appFile atomically:YES];

NSString *txtPath = [documentsDirectory stringByAppendingPathComponent:@"questions.enc"];

    if ([fileManager fileExistsAtPath:txtPath] == NO) {
        NSString *resourcePath = [[NSBundle mainBundle] pathForResource:@"questions" ofType:@"enc"];
        [fileManager copyItemAtPath:resourcePath toPath:txtPath error:&error];
    }

    NSString *filePath1 = [documentsDirectory stringByAppendingPathComponent:@"questions.encr"];

    NSData *passEncryptedData =[[NSData alloc] initWithContentsOfFile:filePath1]  ;
    NSString *pass = @"asdf"; // Insert your password from step 1

    NSData *dataDecrypted = [RNOpenSSLDecryptor decryptData:passEncryptedData withSettings:kRNCryptorAES256Settings password:pass error:&error];

        NSString *appFile = [documentsDirectory stringByAppendingPathComponent:@"questionsDECRYPTED.plist"]; //The Decrypted file saved here
        [dataDecrypted writeToFile:appFile atomically:YES];

NSDictionary *Your_NSDictionary = [NSDictionary dictionaryWithObjectsAndKeys:
                           @"Obj1", @"Key1",
                           @"Obj2", @"Key2", nil];
//store dictionary
NSMutableData *yourData = [[NSMutableData alloc] init];
NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data];
[archiver encodeObject:Your_NSDictionary forKey: @"key"];
[archiver finishEncoding];
[yourData writeToFile:@"FilePath" atomically:YES];

NSString* filePath = [[NSBundle mainBundle] pathForResource:@"Data"
                                                 ofType:@"plist"];
NSDictionary* data = [NSDictionary dictionaryWithContentsOfFile:filePath];
NSMutableDictionary * rootObject;
rootObject = [NSMutableDictionary dictionary];
[rootObject setValue: data forKey:@"accounts"];
[NSKeyedArchiver archiveRootObject: rootObject toFile: path];