In this recipe, we will start to implement additional functionality to our ViewController class, as well as importing some very important header files and extend our class.
Following on from our previous recipe, ensure that our SocialNetworkApp project file is open.
To begin, follow these simple steps as outlined in the given order:
- Open the
ViewController.hinterface file from the Project Navigator. - Next, modify the interface file as shown by the highlighted code sections:
// ViewController.h // SocialNetworkApp // Created by Steven F. Daniel on 11/12/12. // Copyright (c) 2012 GenieSoft Studios. All rights reserved. #import <UIKit/UIKit.h> #import "AppDelegate.h" @interface ViewController : UIViewController<UIActionSheetDelegate, FBRequestDelegate> { AppDelegate *mainDelegate; IBOutlet UIBarButtonItem *loginButton; IBOutlet UIBarButtonItem *postMessage; IBOutlet UIImageView *imgPhoto; IBOutlet UITextView *userInfoDetails; Facebook *facebook; } // Create the required class Setters and Getters @property (nonatomic, strong) UIBarButtonItem *loginButton; @property (nonatomic, strong) UIBarButtonItem *postMessage; @property (nonatomic, strong) UIImageView *imgPhoto; @property (nonatomic, strong) UITextView *userInfoDetails; @property(nonatomic, retain) Facebook *facebook; @property(nonatomic, retain) AppDelegate *mainDelegate; // Declare our Instance methods -(void)SendNotificationRequest; -(void)PostMessagetoWall; -(void)getGraphAPIData; -(void)dialogDidComplete:(FBDialog *)dialog; -(void)request:(FBRequest *)request didLoad:(id)result; -(void)request:(FBRequest *)request didFailWithError:(NSError *)error; @end
- Next, open the
ViewController.mimplementation file from the Project Navigator and modify the implementation file as shown by the highlighted code sections:// ViewController.m // SocialNetworkApp // Created by Steven F. Daniel on 11/12/12. // Copyright (c) 2012 GenieSoft Studios. All rights // reserved. #import "ViewController.h" #import "FBConnect.h" @interface ViewController () @end @implementation ViewController @synthesize mainDelegate, loginButton, postMessage; @synthesize imgPhoto,userInfoDetails, facebook; - (void)viewDidLoad{ [super viewDidLoad]; // Set up our delegate object self.mainDelegate = (AppDelegate *)[[UIApplication sharedApplication]delegate]; self.facebook = mainDelegate.facebook; // Initialize our form fields userInfoDetails.text = @""; } #pragma mark Handle when the login button is pressed. - (IBAction)loginButton:(id)sender{ if ([loginButton.title isEqualToString:@"Sign In"]) { if (![self.facebook isSessionValid]) { NSLog(@"facebook session"); NSArray *permissions = [[NSArray alloc] initWithObjects:@"email",@"publish_actions", nil]; [self.facebook authorize:permissions]; [permissions release]; } else {NSLog(@"session still valid");} [loginButton setTitle:@"Sign Out"]; } else if([loginButton.title isEqualToString:@"Sign Out"]) { [loginButton setTitle:@"Sign In"]; [self.facebook logout:self.mainDelegate]; } }
In this recipe, we started by extending our class to include the UIActionSheetDelegate and FBRequestDelegate class protocols, as well as its methods. We then declared an instance variable called facebook that will enable us to access the Facebook class methods. Next, we added a property instance of the Facebook class to create the class getters and setters and then proceed to synthesize our facebook variable that we defined within the AppDelegate.h interface file.
Next, we import the interface file header information for our FBConnect.h interface file, so that we can access the request dialog class methods. Next, we declare an application delegate object mainDelegate that points to the properties and class methods within our delegate class. Next, we initialize our facebook object within our ViewController to use the same object instance as the one which we instantiated within our delegate class. Finally, we initialize our user info details using UITextView control.
Next, we create our loginButton: method, and check the status of the button. If the button reads Sign In, we use the isSessionValid method of the facebook object to determine if we still have a valid connection to the facebook instance.
If it proves that our session has expired, we initialize and pass to our authorize method of the facebook class permissions to request for accessing the user's e-mail, and allow the iOS to publish to the Open Graph API actions. Finally, we release the memory that has been allocated by our permissions object and then update the title of the button to read Sign Out. If our button reads Sign Out as determined by the loginButton: method, we update the title of the button to read Sign In and then call the logout method of the Facebook class, and then pass in our mainDelegate object. When this method is called, it will call the fbDidLogout method of the FBSessionDelegate within our AppDelegate class to handle any post logout actions and releasing of objects as well as for notifying the user that a successful logout has taken place.
Note
When making a call to the logout method, your application's permissions will not be revoked; it will simply clear the value of your application's access_token. If a user who has previously logged out of your application decides to run it again, they will simply see a notification that they are logging back into your application, not a notification requesting for permissions. For more information on the Facebook protocol methods, refer to the following URL: http://developers.facebook.com/docs/reference/iossdk/#protocols