Sharing on Facebook, Twitter and Google+

[FIXED]     Font of navbar.
[FIXED]     A few compile fixes.
[IMPROVED]  Made properties nonatomic.
[ADDED]     Support for facebook, twitter and google+ sharing.

External/google-plus-ios-sdk/lib/GooglePlusSignInButton.h

@@ -0,0 +1,52 @@
+//
+//  GooglePlusSignInButton.h
+//  Google+ iOS SDK
+//
+//  Copyright 2012 Google Inc.
+//
+//  Usage of this SDK is subject to the Google+ Platform Terms of Service:
+//  https://developers.google.com/+/terms
+//
+
+#import <UIKit/UIKit.h>
+
+@class GooglePlusSignIn;
+@protocol GooglePlusSignInDelegate;
+
+// The various visual styles supported by the GooglePlusSignInButton.
+typedef enum {
+  kGooglePlusSignInButtonStyleNormal,
+  kGooglePlusSignInButtonStyleWide
+} GooglePlusSignInButtonStyle;
+
+// A view that displays the Google+ sign-in button. You can instantiate this
+// class programmatically or from a NIB file. Once instantiated, you should
+// set the client ID and delegate properties and add this view to your own view
+// hierarchy.
+@interface GooglePlusSignInButton : UIView
+
+// The OAuth 2.0 client ID of the application.
+@property(nonatomic, copy) NSString *clientID;
+
+// See GooglePlusSignIn.h for details on this delegate.
+@property(nonatomic, assign) id<GooglePlusSignInDelegate> delegate;
+
+// Actually does the work of signing in with Google+.
+@property(nonatomic, readonly) GooglePlusSignIn *googlePlusSignIn;
+
+// The OAuth 2.0 scopes for the APIs that you are using. This is used to fetch
+// an OAuth 2.0 token. By default, this is set to the
+// https://www.googleapis.com/auth/plus.me scope.
+@property(nonatomic, copy) NSArray *scope;
+
+// Sets the sign-in button. The default style is normal.
+- (void)setStyle:(GooglePlusSignInButtonStyle)style;
+
+// This method should be called from your |UIApplicationDelegate|'s
+// |application:openURL:sourceApplication:annotation|. Returns |YES| if
+// |GooglePlusSignInButton| handled this URL.
+- (BOOL)handleURL:(NSURL *)url
+    sourceApplication:(NSString *)sourceApplication
+           annotation:(id)annotation;
+
+@end