iOS Forensics Cookbook

First, we will find out where in simulators and iPhones our document directories are present. To find the path, we need to write some code in our viewDidLoad method. Add the following line of code in viewDidLoad:

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSLog(@"%@", documentsDirectory);

In the preceding code, first we fetch the existing path in our path's array. Now, we will take the first object of our path array in a string that means our string contains one path for our directory. This code will print the path for document directory of the simulator or device wherever you are running the code.

To create the folder in documentsDirectory, run the following code:

NSString *dataPath = [documentsDirectory stringByAppendingPathComponent:@"/MyFolder"];
if (![[NSFileManager defaultManager] fileExistsAtPath:dataPath])
  [[NSFileManager defaultManager] createDirectoryAtPath:dataPath withIntermediateDirectories:NO attributes:nil error:nil];

In the preceding code snippet, the [documentsDirectory stringByAppendingPathComponent:@"/MyFolder"] line will create our folder in the Document directory and the last code of NSFileManager will check whether that dataPath exists or not; if it does not exist, then it will create a new path.

Now, compile and run the project; you should be able to see the path of Document directories in your project console. This should look like the following screenshot:

Now, go to Finder; from the options, select Go to Folder and paste the documentsDirectory path from the console. This will navigate you to the Documents directory of the simulator. The Documents directory will look like the following screenshot:

Now, we will create a .txt file in our folder (which we created in the document directory). Customize the code in viewDidLoad: as follows:

dataPath = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject] stringByAppendingPathComponent:@"myfile.txt"];
NSLog(@"%@", dataPath);

The preceding code will create a .txt file of name myfile.txt.

To write something into the file, add the following code:

NSError *error;
NSString *stringToWrite = @"1\n2\n3\n4";
dataPath = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject] stringByAppendingPathComponent:@"myfile.txt"];
[stringToWrite writeToFile:dataPath atomically:YES encoding:NSUTF8StringEncoding error:&error];

The writeToFile method is used to write data in our file.

Now, to read the data from the file, there's the stringWithContentsOfFile method. So add the following method inside the code:

NSString *str = [NSString stringWithContentsOfFile:dataPath encoding:NSUTF8StringEncoding error:&error];
NSLog(@"%@", str);

To see the mayflies.txt file in the Documents directory, go to the GoToFolder finder and paste dataPath from the console. It will take you to mayflies.txt. The final file should look something like the following screenshot:

In the screenshot, you can see the two files have been created. As per our code, we have created myfile.txt and myfile.pdf. We have also created MyFolder in the same Documents folder of the app.

Open Xcode and go to File | New | File, and then, navigate to iOS | Application | Single View Application. In the popup, provide the product name SQLite Sample. It should look like the following screenshot:

Click on Next and save the project. After creating the project, we need to add a SQLite library (libsqlite3.dylib). To add this library, make sure that the General tab is open. Then, scroll down to the Linked Frameworks and Libraries section and click on the + button and add the libsqlite3.dylib library to our project:

Before we can create a database, we need to import the SQLite framework at the top of the screen. Now, declare a variable for sqlite3 and create a NSString property to store the database path. Within the main Xcode project navigator, select the DatabaseViewController.h file and modify it as follows:

#import <UIKit/UIKit.h>
#import <sqlite3.h>

@interface DatabaseViewController : UIViewController

@property (strong, nonatomic) NSString *pathDB;
@property (nonatomic) sqlite3 *sqlDB;
@end

Now it's time to design our user interface for the SQLite iPhone application. Select the storyboard and then drag and drop the table view to the view along with the table view cell. For tableviewcell, select the Subtitle style from the attribute and give it an identifier (for example, cell); and add one button on the navigation bar (style -> add). Make an outlet connection of the table view and button to ViewController.h.

The final screen should look like the following screenshot:

Now we will have to connect the table view outlet with the code. For that, press Ctrl and drag the tableView object to the ViewController.h file. Once connected, you should be able to see the connection in the dialog box with an establish outlet connection named tableView. Repeat the steps to establish the action connections for all the other UI components in view.

Once the connections are established for all, on completion of these steps, the ViewController.h file should read as follows:

#import <UIKit/UIKit.h>
#import <sqlite3.h>

@interface ViewController: UIViewController <UITableViewDataSource, UITableViewDelegate>

@property (strong, nonatomic) NSString *pathDB;
@property (nonatomic) sqlite3 *sqlDB;
@property (weak, nonatomic) IBOutlet UITableView *tableView;

(IBAction)navigateToNextView:(id)sender;

@end

Now we need to check whether the database file already exists or not. If it is not there, then we need to create the database, path, and table. To accomplish this, we need to write some code in our viewDidLoad method. So go to the ViewController.m file and modify the viewDidLoad method as follows:

- (void)viewDidLoad {
  [super viewDidLoad];
  NSString *directory;
  NSArray *dirPaths;
  dirPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
  NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
  NSString *documentsDirectory = [paths objectAtIndex:0];
  NSString *dataPath = [documentsDirectory stringByAppendingPathComponent:@"/MyFolder"];
  if (![[NSFileManager defaultManager] fileExistsAtPath:dataPath])
    [[NSFileManager defaultManager] createDirectoryAtPath:dataPath withIntermediateDirectories:NO attributes:nil error:nil];
  directory = dirPaths[0];
  _pathDB = [[NSString alloc]
  initWithString: [directory stringByAppendingPathComponent:@"employee.db"]];
  NSFileManager *filemgr = [NSFileManager defaultManager];
  if ([filemgr fileExistsAtPath: _pathDB] == NO)
  {
    const char *dbpath = [_pathDB UTF8String];
    if (sqlite3_open(dbpath, &_sqlDB) == SQLITE_OK)
    {
      char *errMsg;
      const char *sql_stmt =
        "CREATE TABLE IF NOT EXISTS EMPLOYEE (ID INTEGER PRIMARY KEY AUTOINCREMENT, NAME TEXT, DESIGNATION TEXT)";

      if (sqlite3_exec(_sqlDB, sql_stmt, NULL, NULL, &errMsg) != SQLITE_OK)
      {
        NSLog(@"Failed to create table");
      }
      sqlite3_close(_sqlDB);
    } else {
      NSLog(@"Failed to open/create table");
  }
}

The code in the preceding method performs the following tasks:

First, we identify the paths available in our directory and store them in an array (dirPaths). Then, we create the instance of NSFileManager and use it to detect whether the database has been created or not. If the file has not been created, then we create the database via a call to the SQLite sqlite3_open() function and create the table as well. And at last, we close the database.

Create a new class named SecondViewController. Go to the storyboard and drag one view controller to the canvas. Design the UI according to the following screenshot:

Now make an outlet and action connection for this.

Create some properties in SecondViewController.h:

@property (strong, nonatomic) NSString *pathDB;
@property (nonatomic) sqlite3 *sqlDB;

In addition, to save the data first, we need to check whether the database is open or not; if it is open, then write a query to insert the data in our table. After writing the data in our table, clear the text present in the text fields. At last, close the database as well.

In order to implement this behavior, we need to modify the save method:

- (IBAction)saveButton:(id)sender {
  sqlite3_stmt *statement;
  const char *dbpath = [_pathDB UTF8String];
  if (sqlite3_open(dbpath, &_sqlDB) == SQLITE_OK)
  {
    NSString *sqlQuery = [NSString stringWithFormat: @"INSERT INTO EMPLOYEE (name, designation) VALUES (\"%@\",\"%@\")",self.nameTextField.text, self.designationTextField.text];

    const char *sqlSTMNT = [sqlQuery UTF8String];
    sqlite3_prepare_v2(_sqlDB, sqlSTMNT,
    -1, &statement, NULL);
        if (sqlite3_step(statement) == SQLITE_DONE)
        {
            self.nameTextField.text = @"";
            self.designationTextField.text = @"";
        } else {
            NSLog(@"Failed to add contact");
        }
        sqlite3_finalize(statement);
        sqlite3_close(_sqlDB);
    }
}

Now we want to populate this saved data in tableview. To achieve this task, go to ViewController.m and create one mutable array using the following line of code and initialize it in viewDidLoad. This array is used to save our SQLite data:

NSMutableArray *dataFromSQL;

In the same class, add the following code to the action button to push the view to new view:

SecondViewController *secondView = [self.storyboard instantiateViewControllerWithIdentifier:@"SecondViewController"];
secondView.pathDB = self.pathDB;
secondView.sqlDB = self.sqlDB;
[self.navigationController pushViewController:secondView animated:YES];

Create the v iewWillAppear method in the ViewController class and modify it as in the following code:

-(void)viewWillAppear:(BOOL)animated
{
  [super viewWillAppear:animated];
  [dataFromSQL removeAllObjects];
  [self.tableView reloadData];
  const char *dbpath = [_pathDB UTF8String];
  sqlite3_stmt *statement;

  if (sqlite3_open(dbpath, &_sqlDB) == SQLITE_OK)
  {
    NSString *querySQL = [NSString stringWithFormat:
      @"SELECT name, designation FROM EMPLOYEE"];

    const char *query_stmt = [querySQL UTF8String];

    if (sqlite3_prepare_v2(_sqlDB, query_stmt, -1, &statement, NULL) == SQLITE_OK)
    {
      while (sqlite3_step(statement) == SQLITE_ROW)
      {
        NSString *name = [[NSString alloc] initWithUTF8String:
        (const char *) sqlite3_column_text(statement, 0)];

        NSString *designation = [[NSString alloc] initWithUTF8String:
        (const char *) sqlite3_column_text(statement, 1)];
        NSString *string = [NSString stringWithFormat:@"%@,%@", name,designation];
        [dataFromSQL addObject:string];
      }
      [self.tableView reloadData];
      sqlite3_finalize(statement);
    }
    sqlite3_close(_sqlDB);
  }
}

In the preceding code, first we open SQLite and then we fire a query SELECT name, designation FROM EMPLOYEE through which we can get all the values from the database. After that, we will make a loop to store the values one by one in our mutable array (dataFromSQL). After storing all the values, we will reload the tableview.

Modify the tableview data source and the delegate method as follows, in ViewController.m:

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    return dataFromSQL.count;
}

(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{

  static NSString *CellIdentifier = @"GBInboxCell";
  UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

  if (cell == nil) {
    cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier];
  }

  if (dataFromSQL.count>0) {
    NSString *string = [dataFromSQL objectAtIndex:indexPath.row];
    NSArray *array = [string componentsSeparatedByString:@","];
    cell.textLabel.text = array[0];
    cell.detailTextLabel.text =array[1];

  }
  return cell;
}

The final step is to build and run the application. Feed the contact details in the second page of the application:

Now click on the Save button to save your contact details to the database.

Now, when you go back to the Employee List view, you will see the newly saved data in your table view:

From the File menu, select the option to create a new project.

Then, select the Single View Application option. Make sure that while creating the project, the Use Core Data checkbox is checked.

Then, click on Next and select a location to save your project. Now you will see that the Xcode has created a new project for us and will launch the project window.

To use the core data in an application, first we will have to create the entity for the CoreData application. For this, select the CoreData.xcdatamodeld file and load it in the entity editor:

In order to add new entities to the data model, click on the Add Entity button, which is located in the bottom bar. Once the entity is created, double-click on New Entity and change its name to Employee.

Once the entity is created, we can now add attributes for it in order to represent the data for the model. Click on the Add Attribute button (+) to add attributes to the entity. For each attribute that is added, set the appropriate type of data. Similarly, add all the attributes one after another.

Now we will create the user interface for the application and will connect all the UI components with their respective IBOutlets and actions. Here, we are following a design similar to our SQLite sample; over and above design, we will add one more class, which is SecondViewController:

Check all the IBOutlet connections in the SecondViewController.h file, all the properties should have a dark circle indicator. Then we need to import the AppDelegate.h file at the top. After all the changes the class will look similar to following code:

#import <UIKit/UIKit.h>
#import "AppDelegate.h"

@interface SecondViewController : UIViewController
@property (weak, nonatomic) IBOutlet UITextField *nameTextField;
@property (weak, nonatomic) IBOutlet UITextField *designationTextField;

- (IBAction)saveButton:(id)sender;
@end

When the user touches the Save button, the save method is called. We need to implement the code to obtain the managed object context and create and store managed objects containing the data entered by the user. Select the ViewController.m file, scroll down and save the method, and implement the code as follows:

- (IBAction)saveButton:(id)sender {
  AppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];

  NSManagedObjectContext *context =
  [appDelegate managedObjectContext];
  NSManagedObject *newContact;
  newContact = [NSEntityDescription insertNewObjectForEntityForName:@"Employee" inManagedObjectContext:context];

    [newContact setValue: _nameTextField.text forKey:@"name"];
    [newContact setValue: _designationTextField.text forKey:@"designation"];
  _nameTextField.text = @"";
  _designationTextField.text = @"";
}

In the preceding code, we created a shared instance of [UIApplication sharedApplication]. This code snippet will always give the same instance every time. Afterwards, it will create nsmanagedobject with the entity we created in CoreData.xcdatamodel, and then it will set the values for the keys.

Now we need to populate the same data in our tableview. To achieve that, go to ViewController.m, create one mutable array (for example, dataFromCore) to save our data from CoreData to local, and modify viewWillAppear:

-(void)viewWillAppear:(BOOL)animated
{
  [super viewWillAppear:animated];

  [dataFromCore removeAllObjects];
  [self.tableView reloadData];
  AppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];
  NSManagedObject *matches = nil;
  NSManagedObjectContext *context = [appDelegate managedObjectContext];

  NSEntityDescription *entityDesc = [NSEntityDescription entityForName:@"Employee" inManagedObjectContext:context];

  NSFetchRequest *request = [[NSFetchRequest alloc] init];
  [request setEntity:entityDesc];

  NSError *error1 = nil;
  NSArray *results = [context executeFetchRequest:request error:&error1];
  if (error1 != nil) {
    NSLog(@"%@", error1);
  }
  else {
    for (matches in results) {
      NSLog(@"%@.....%@", [matches valueForKey:@"name"],[matches valueForKey:@"designation"]);
      NSString *string = [NSString stringWithFormat:@"%@,%@",[matches valueForKey:@"name"],[matches valueForKey:@"designation"]];
      [dataFromCore addObject:string];

    }
  }
  [self.tableView reloadData];
}

Again, it will create the shared instance of [UIApplication sharedApplication] and it will return the same instance as previously. Now, we are fetching the data from NSFetchRequest using NSEntityDescription and saving the result in one array. After that, we retrieve the values from the keys, one by one, and add them to our mutable array (dataFromCore), and at last, reload our tableview.

Our tableview methods should look similar to the following code. If they do not, then modify the code:

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
  return dataFromCore.count;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
  static NSString *CellIdentifier = @"GBInboxCell";
  UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
  if (cell == nil) {
    cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier];
  }
  if (dataFromCore.count>0) {
    NSString *string = [dataFromCore objectAtIndex:indexPath.row];
    NSArray *array = [string componentsSeparatedByString:@","];
    cell.textLabel.text = array[0];
    cell.detailTextLabel.text =array[1];

  }
  return cell;
}

The final step is to build and run the application. Enter the text in the second view and hit Save to save your contact details in our database: