Pinter Computing

When you design an iPhone, iPad view in the Xcode Builder and place a Scroll View on the View Controller you can make the page larger than the physical size of the screen of the device. To see the whole view set the size of the View.

• Open the Story Board in Xcode
• Shift Control Click the view to display the list of objects under the mouse
• Select the View Controller
  
• Open the Utilities view
• Select the Attributes inspector
• Set the Size to Freeform
  
• Shift Control click the view again
• Select the View
  
• Select the Size inspector
• Set the Height to a larger number
  

This will extend the size of the View Controller, but most likely will move the objects to occupy the whole space.

If some of the objects disappear from the visible area of the View, you can set the coordinates of the upper left corner to move them back to the visible region.

• Open the Storyboard
• Open the Document Outline view
• Select the object you want to move
  
• Open the Utilities view
• Select the Size inspector
• Set the Y coordinate to a number that is within the visible area
  
• Now you can click the object the move it with the mouse

In this part of the series we will continue the development of our data store app that we set up in the first part of the series.

Create the Data Model

• Open your sample application that you created in the first part
• Open the Project Navigator
• Select the Supporting Files group
• Click the plus (+) sign in the lower left corner of the screen
• Select New File… in the pop-up
• Under iOS select Core Data on the left side
• Select the Data Model icon in the middle of the window
•  Click the Next to save the file

Add an Entity to the data model

• Open the .xdatamodeld file in the Project Navigator
• Click the Add Entity button at the bottom of the screen
  
• In the upper right corner of the window under Entities name the entity Event
  
  

Add an attribute to the Entity

• Click the plus (+) sign at the bottom of the Attribute section of the window
  
• Name the attribute creationDate, and set the type to Date in the pop-up menu
  
• Add another attribute, name it as latitude and set the type to Double
• Add a third attribute, name it longitude and set the type to Double
  As you are adding the new attributes the rows jump around to be displayed alphabetically, so make sure you are setting the type of the correct row.
  The attributes of the Event entity should look like this
  

Create a custom class to represent the Event entity to be able to create methods for the entity

• Select the Event entity on the window
• In the File menu select New -> New File…
• In the New File dialog, select NSManagedObject subclass
  
• Click the Next button
• Save the file in the project folder

Import the new class into the ViewController

• Add the following to the RootViewController.m implementation file

  #import "Event.h"

This article will guide you to create an app that stores data on the user’s device. To create our sample app to store data on the user’s device

• Start Xcode, the Apple IDE for IOS development
• Create a new project
• Open the AppDelegate.h file and enter the following into the @interface section before the @end

  @property (nonatomic, retain, readonly) NSManagedObjectContext *managedObjectContext;
  @property (nonatomic, retain, readonly) NSManagedObjectModel *managedObjectModel;
  @property (nonatomic, retain, readonly) NSPersistentStoreCoordinator *persistentStoreCoordinator;
  
  - (NSURL *)applicationDocumentsDirectory;
  - (void)saveContext;

  The lines above define three properties and two methods. The properties provide access to the Core Data framework of IOS, and the saveContext method will save you changes in the data file.

The Apple Core Data framework uses the following terminology

managed object

The table row

managed object context

Table rows that are in the memory and not saved to the database yet

managed object model

Describes the database, stores the relationships between the tables

entity description

Describes a table

persistent store coordinator

Manages a collection of persistent object stores, data files on the disk

• In Xcode create a new class: RootViewController and make it the subclass of UITableViewController

• Open the RootViewController.h header file and replace the content with the following

#import <CoreLocation/CoreLocation.h>

@interface RootViewController : UITableViewController  {

    NSMutableArray *eventsArray;
    NSManagedObjectContext *managedObjectContext;

    CLLocationManager *locationManager;
    UIBarButtonItem *addButton;
}

@property (nonatomic, retain) NSMutableArray *eventsArray;
@property (nonatomic, retain) NSManagedObjectContext *managedObjectContext;

@property (nonatomic, retain) CLLocationManager *locationManager;
@property (nonatomic, retain) UIBarButtonItem *addButton;

@end

• Open the RootViewController.m class file and add the following to the @implementation section

// Synthesize the properties to tell the compiler how to name them
@synthesize eventsArray;
@synthesize managedObjectContext;
@synthesize addButton;
@synthesize locationManager;

• Write the Accessor Method for the Core Location Manager

// Create an accessor method to dynamically create the Core Location manager on demand
- (CLLocationManager *)locationManager {

    if (locationManager != nil) {
        return locationManager;
    }

    locationManager = [[CLLocationManager alloc] init];
    locationManager.desiredAccuracy = kCLLocationAccuracyNearestTenMeters;
    locationManager.delegate = self;

    return locationManager;
}

• Add the following two Core Location manager delegate methods

// Implement two delegate methods to enable and disable the Add button as appropriate.
// If the Core Location manager is generating updates, then enable the button;
// if the Core Location manager is failing, then disable the button
- (void)locationManager:(CLLocationManager *)manager
    didUpdateToLocation:(CLLocation *)newLocation
           fromLocation:(CLLocation *)oldLocation {
    addButton.enabled = YES;
}

- (void)locationManager:(CLLocationManager *)manager
       didFailWithError:(NSError *)error {
    addButton.enabled = NO;
}

• Replace the implementation of viewDidLoad with the following:

- (void)viewDidLoad {

    [super viewDidLoad];

    // Set the title.
    self.title = @"Locations";

    // Set up the buttons.
    self.navigationItem.leftBarButtonItem = self.editButtonItem;

    // The viewDidLoad method needs to set up the Core Location manager and the Add and Edit buttons.
    addButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAdd
    target:self action:@selector(addEvent)];
    addButton.enabled = NO;
    self.navigationItem.rightBarButtonItem = addButton;

    // Start the location manager.
    [[self locationManager] startUpdatingLocation];
}

• Implement Methods for Memory Management

// Replace the existing implementations of viewDidUnload and dealloc. The implementation of viewDidUnload // should relinquish ownership of anything created in viewDidLoad that can be recreated.
- (void)viewDidUnload {
    self.eventsArray = nil;
    self.locationManager = nil;
    self.addButton = nil;
}

Add the Navigation Bar to the top of the view

• Open the Story Board in the Project Navigator
• Select the FirstView
• Drag a Navigation Bar to the top of the view from the Object library
• Drag a Bar Button Item to the left side of the Navigation Bar and set the Identifier to Edit
• Drag a Bar Button Item to the right side of the Navigation Bar and set the Identifier to Add

Configuring the Application Delegate

The application delegate is responsible for creating and configuring the root view controller and a navigation controller to contain it.

Add the Navigation Controller Property

• In the application delegate’s header file (AppDelegate.h), before the @interface section add an instance variable:

  UINavigationController *navigationController;

• Add the property declaration:

  @property (nonatomic, retain) UINavigationController *navigationController;

Implement the Application Delegate

In the application delegate’s implementation file (AppDelegate.m):

• Before the @implementation block of the application delegate class, import the RootViewController class’s header file:

  #import "RootViewController.h"

• In the @implementation block of the application delegate class, synthesize the navigation controller property:

  @synthesize navigationController;

   

• Replace your application delegate’s application:didFinishLaunchingWithOptions: method with the following implementation:

  - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
  
      RootViewController *rootViewController = [[RootViewController alloc]
      initWithStyle:UITableViewStylePlain];
  
      NSManagedObjectContext *context = [self managedObjectContext];
      if (!context) {
          // Handle the error.
      }
      // Pass the managed object context to the view controller.
      rootViewController.managedObjectContext = context;
  
      UINavigationController *aNavigationController = [[UINavigationController alloc]
      initWithRootViewController:rootViewController];
      self.navigationController = aNavigationController;
  
      [window addSubview:[navigationController view]];
      [window makeKeyAndVisible];
  
      return YES;
  }

When you need to display date and time on your app’s screen you need an easy way to convert NSDate objects to NSString objects. Objective-C  contains methods to do the conversion, but the syntax is not simple. It is much easier to create a method that does the conversion and call that in a central place.

Create a method to convert NSDate objects to NSString using the current date format of the device.

Add a new class to the project

• Click the + sign in the lower left corner of the Project Navigator
• Select New File… in the pop-up menu
• Select IOS -> Cocoa Touch -> Objective-C class
• Click the Next button
• Enter CommonMenthods into the Class field
• Select NSObject in the Subclass of list
• Click the Next button
• Click the Create button to save the file in the project folder

Add three method signatures to the CommonMethods class

• Open the CommonMethods.h file
• Insert the following code into the @interface section

  + (NSString *)getDateShortString:(NSDate *)date;
  + (NSString *)getTimeShortString:(NSDate *)date;
  + (NSString *)getDateAndTimeShortString:(NSDate *)date;
  
  

Add the three methods to the implementation file

• Open the CommonMethods.m file
• Insert the following code into the@implementation section of the file

  // Returns the short date as a string
  + (NSString *)getDateShortString:(NSDate *)date {
      
      NSString *stringFromDate = [NSDateFormatter localizedStringFromDate:date
                                                                dateStyle:NSDateFormatterShortStyle
                                                                timeStyle:NSDateFormatterNoStyle];
      
      return stringFromDate;
  }
  
  // Returns the short time as a string
  + (NSString *)getTimeShortString:(NSDate *)date {
      
      NSString *stringFromDate = [NSDateFormatter localizedStringFromDate:date
                                                                dateStyle:NSDateFormatterNoStyle
                                                                timeStyle:NSDateFormatterShortStyle];
      
      return stringFromDate;
  }
  
  
  // Returns the short date and time as a string
  + (NSString *)getDateAndTimeShortString:(NSDate *)date {
      
      NSString *stringFromDate = [NSDateFormatter localizedStringFromDate:date
                                                                dateStyle:NSDateFormatterShortStyle
                                                                timeStyle:NSDateFormatterShortStyle];
      
      return stringFromDate;
  }
  

To use the new methods

Make the methods available in the class

• Import the CommonMethods.h file into the class where you want to use the method
• Insert the following line under the existing #import statement

  #import "lpCommonMethods.h"

Call the methods

• Use the following syntax to display the date and time in short format set by the user

  self.startDateLabel.text = [CommonMethods getDateAndTimeShortString:self.startDate];

  where
  startDateLabel is a label on the view
  startDate is the NSDate object

Segue types

Segues are connections between views, so one view can call the other when the user pushes a button, or any specific object.

The Modal Segue

When the two views do not need to share information, like a login screen

The Push Segue

The push segue can pass data between the views and handle memory. This type of segue is needed for the navigation controller and tab bar controller.

Creating a Modal Segue

Add a button to the first view that will open the second view

• In Xcode open the Storyboard of your application
• Open the Utilities View in the upper right corner of the screen and select the Object library

• Drag a Text Field to the first view
• Drag a Round Rect Button to the first view and enter Open Second Page as the title
  

Add a new view to the Storyboard

• From the Object library drag a View Controller to the storyboard
• Drag a Text Field from the Object library to the second view
• Drag a Round Rect Button from the Object library to the second view and enter Back to First Page to the title
  

Create the segue between the views

• Press the Control button on the keyboard and drag from the button on first view to the new view controller and release the control key and the mouse button
  
• In the popup select modal
  
  

Add the Text field to the interface of the first view

• Open the ViewController.h of the new view in the Assistant Editor
• Press the Control button and drag from the text field to the @interface section of the ViewController.h file
• In the popup type firstTextField to the Name field and click the Connect button
  

Add the button to the interface of the first view

• Press the Control key on the keyboard and drag the button from the first view to the @interface section of the ViewController.h file. Set the 
  • Connection to Action
  • Name to showSecondView: (including the colon)
  • Click the Connect button
    

Create a a UIViewController class for the new View Controller

• In the lower left corner of the project navigator click the plus sign (+)
• Select New File... from the popup menu
• On the popup window select Objective-C Class under IOS Cocoa Touch
• Click the Next button
• Set the name of the class to SecondViewController
• Set the “Subclass of” to UIViewController
• Click the Create button to place the new class into the project folder

Connect the new class to the View

• Open the Storyboard and select the new view
• In the Identity Inspector elect SecondViewController in the Class list

Add the Text field to the interface of the second view

• Open the SecondViewController.h of the new view in the Assistant Editor
• Press the Control button and drag from the text field to the @interface section of the SecondViewController.h file
• In the popup type secondTextField to the Name field and click the Connect button
  

Add the button to the interface of the second view

• Press the Control key on the keyboard and drag the button from the second view to the @interface section of the SecondViewController.h file. Set the
  • Connection to Action
  • Name to returnToFirstView: (including the colon)
  • Click the Connect button
    

View two files side-by-side

• Open the Project Navigator
• Click the first file in the Navigator
• Option-Click the second file in the Navigator

The two files are displayed next to each other, so you can compare them and copy code between them.

Using tabs

In the Apple Xcode IDE you can use tabs to quickly switch between documents.

It looks like tabs are not the native way to open documents, because opening documents in tabs is not so intuitive.  To open a document in a new tab:

• In the View menu select Show Tab Bar. This will show an empty bar for the tabs.
• In the File menu select New -> Tab. The currently open document appears again in the new tab.
• To open another document in a new tab
  • In the File menu select New -> Tab. The same, currently selected document opens third times in the new tab.
  • Select a new document in the project navigator for the new tab.

The positive side of this is that the multiple instances of the same document are synchronized, so a change in one instance is instantly reflected in the other instances.

 Using multiple windows

The advantage of this setup is to be able to configure the separate Xcode windows differently, for example one for code editing, the other for graphical view design.

• In the File menu select New -> Window

Set up debugging

With the default settings in Xcode if there is an error in your app the user interface does not display the line where the error occurred. You can instruct Xcode to stop the execution on the line of code that will cause an error:

• In the Debug menu select Breakpoints -> Create Exception Breakpoint… 

Xcode creates a new breakpoint called All Exceptions. When an exception (error) happens in your application Xcode will stop on the line that caused it.

Debug your app in the iOS Simulator or on your Apple device

• Open the …ViewController.m on the project navigator
• Find the self.label.text = greeting; statement close to the end of the file
• Click the gutter (the wider light gray area) on the left side to place a break point

• Select the iPhone Simulator scheme next to the Stop button on the top of the screen
• Click the Run button to execute the application in the iOS simulator
• In the simulator enter your name in the text field
• Click the Done button on the virtual keyboard
• Click the Hello button on the simulator screen
• The program execution will stop at the break point and show the selected line in the code editor

To remove the break point click and drag it away from the gutter

Accessing the Xcode Help

• Control click anywhere in the code editor
• In the pop- up context menu one of the last items is the Source Editor Help

Monitor the performance of your app

• Start Xcode and open your project
• In the Product menu select Perform Action -> Profile Without Building
• The Profile window opens
• On the left side select All to see all available tools
• For example to test for memory leaks select the Leaks template and click Profile
• Use the application in the simulator to provide data for the profiler
• In the iOS Simulator menu select Quit iOS Simulator to close the simulator
• The Allocations option on the left side shows the memory allocation history during the execution

Manage versions of your app

Xcode can create snapshots to store multiple versions of your app in case you make a modification that stops your app working, or you accidentally delete your source code

To manually create a snapshot

• In the File menu select Create Snapshot
• Enter a name for the snapshot, so later you can find it

To see the snapshots

• Open the Organizer in the upper right corner of the screen
• Click the Project button on the top of the window

Xcode also supports the Git and Subversion source control management systems (SCM) to coordinate work among multiple developers.

In the prior parts of the series we have created a simple iOS application and tested it in the iOS Simulator. The real gratification comes when we can see our own app on a real device, an iPhone, iPod or iPad. In this article we will deploy the app to an Apple device.

Get an Apple Developer account

You have to apply for a developer account to be able to deploy your app to an Apple device. The subscription fee is $99 + tax per year.

To open a developer account go to developer.apple.com

Once you receive the iOS Developer Program activation code via email you are ready to deploy the app to a real device.

The email contains an activation code, that is also a link to activate your account. Once you activated the account wait 5 minutes before trying to set up your device in Xcode. The Apple system needs some time to recognize the account activation.

Set up your Apple device

• Start Xcode
• Unlock your Apple device with the pass code
• Connect the Apple device to the Macintosh computer
• Open the Device organizer by clicking the Organizer button in the upper right corner of the Xcode screen
• Select the device on the left side
• Click the Use for Development button in the middle of the screen
  If the button is not visible click the Add to Portal button at the bottom of the screen

• Enter your Apple Id and password that you used to register as an Apple developer
• Xcode will offer you to generate security certificates, allow the application to do that
• At the end of the certification generation process save the certificates on your computer, so you will be able to carry them to another Mac to develop on that machine too.
• Close Xcode to force the application to get the latest certificate information from the Apple Developer web site

Deploy the application on the Apple device

• Unlock your Apple device with the pass code
• Connect the Apple device to the Macintosh computer
• Start Xcode and open the project you want to deploy to the device
• In the Product menu select Scheme -> Edit Scheme… to open the scheme editor
• Select your device in the Destination pop-up menu

• Click OK to close the schema editor

• Click the Run button in the upper right corner of the screen

You may get the following error message:

“Code Signing Error. A valid provisioning profile matching the application’s Identifier … could not be found”

Follow the steps in the answer at http://stackoverflow.com/questions/16155613/a-valid-provisioning-profile-matching-the-applications-identifier-could-not-be

• A new icon appears on the screen of your Apple device. Tap it, now you can run your brand new application on your own device!

In this article we will make our application work. We already created a simple application and added a Text field, a Label and a Button to the view. We created connections between the user interface elements and the View Controller.

To make more room to work, close the Utilities area by clicking the Utilities button in the View group in the upper right corner of the screen or in the View -> Utilities menu click Hide Utilities

Create a Property to store your name

To be able to work with the data entered into the text field we have to create a property to store it and make it available for other processes. The property is a placeholder where we store values.

• In the project navigator on the left side of the screen select the …ViewController.h
• Before the @end statement write the following:

  @property (copy, nonatomic) NSString *userName;

You can copy the text into the editor, but if you choose to type it, Xcode will help you to complete the words. Just hit Return to accept the suggestions.

As you continue to type Xcode will show selection lists to help you. Use the arrow keys to select the appropriate item and press Return.

Make the button work

In the previous article, Part 2,we already connected the button to the controller, now we will tell the controller what to do when the user clicks the button.

• In the project navigator on the left side of the screen select the …ViewController.m item
• Scroll down to the bottom to see the implementation of the changeGreeting: method at the end of the @implementation section
• Add lines to the method, it should look like the text below. The first and last lines (the method definition and the closing bracket) are already there, to overwrite them copy the text below, select the first and last line in the editor and replace them with the full text.

- (IBAction)changeGreeting:(id)sender {

    self.userName = self.textField.text;

    NSString *nameString = self.userName;
    if ([nameString length] == 0) {
        nameString = @"World";
    }
    NSString *greeting = [[NSString alloc] initWithFormat:@"Hello, %@!", nameString];
    self.label.text = greeting;
}

You can run your app now to make sure all parts are correct, but it is not done yet.

• Click the button on the simulated screen and  “Hello, World!” should appear in the the label.
• If you click the text field you can enter letters there, but there is no way yet to close the automatically appearing keyboard

Make the keyboard disappear

The text field cannot close the keyboard, but it can ask the View Controller to act in behalf of it, so we will delegate the work to the View Controller

• Stop the simulator by clicking the Stop button in the upper right corner of the screen

Teach the View Controller what to do

• Select the …ViewController.m in the project navigator on the left side of the screen
• At the bottom of the file before the @end statement enter the following. The easiest way to to this is to copy and paste the code.

- (BOOL)textFieldShouldReturn:(UITextField *)theTextField {
    if (theTextField == self.textField) {
        [theTextField resignFirstResponder];
    }
    return YES;
}

In the method the resignFirstResponder instruction will close the keyboard.

Set up the View Controller to work on behalf of the text field

• In the project navigator select the …ViewController.h item
• To the end of the @interface line add the following:  <UITextFieldDelegate>The line should look like this:

  @interface HelloWorldViewController : UIViewController <UITextFieldDelegate>

  If there is already something between the < and > signs, just add ,UITextFieldDelegate starting with a comma (,) between the < and > signs.

Test your application

• Click the Run button in the upper right corner of the screen

The application should behave as you expect it:

• When you click the text field the keyboard appears
• When you enter your name the letters show up in the text field
• When you click the Done button on the keyboard the keyboard disappears
• When you click the button on the screen “Hello, your name” appears in the label

Congratulations, you just created your first working iPhone, iPod, iPad app!