Reader Level:

Bluetooth Chat App in iPhone

By Sachin Bhardwaj on Jan 31 2013
In this article I will implement Bluetooth in an iPhone.
    • Like
    • Love It
    • Awesome
    • Interesting
    • It's Okay
    • Thumbs Down
  • 9.8k
  • 0


In this article I will create a Single View application. Here we implement Bluetooth in iPhone. For that we use "GameKit Framework" that is required to implement Bluetooth. It is a free app for chatting purposes.

To understand it we use the following.

Step 1

Open XCode by double-clicking on it.

Step 2

Create a New XCode Project by clicking on it.

Step 3

Now Select Single View Application and click on Next.

Step 4

Now provide your Product Name and Company Identifier.

Step 5

Select the location where you want to save your project and click on Create.

Step 6 

First we import the framework "GameKit" that is required.


Step 7

Now here we write the code.


#import <UIKit/UIKit.h>
@class ViewController;
@interface AppDelegate : UIResponder <UIApplicationDelegate>
@property (strong, nonatomic) UIWindow *window;
@property (strong, nonatomic) ViewController *viewController;


#import "AppDelegate.h"
#import "ViewController.h"
@implementation AppDelegate
- (void)dealloc
[_window release];
[_viewController release];
[super dealloc];
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];
// Override point for customization after application launch.
self.viewController = [[[ViewController alloc] initWithNibName:@"ViewController" bundle:nil] autorelease];
self.window.rootViewController = self.viewController;
[self.window makeKeyAndVisible];
return YES;


#import <UIKit/UIKit.h>
#import <GameKit/GameKit.h>
@interface ViewController : UIViewController<GKSessionDelegate, GKPeerPickerControllerDelegate>
@property (strong, nonatomic) UILabel *messageReceivedLabel;
@property (strong, nonatomic) UITextField *messageToSendTextField;
@property (strong, nonatomic) GKSession *session;
@property (strong, nonatomic) UIButton *sendButton;


#import "ViewController.h"
@interface ViewController ()
- (void)sendMessage:(id)sender;
- (void)connectToDevice:(id)sender;

@implementation ViewController
@synthesize messageReceivedLabel = _messageReceivedLabel;
@synthesize messageToSendTextField = _messageToSendTextField;
@synthesize session = _session;
@synthesize sendButton = _sendButton;
- (void)connectToDevice:(id)sender
if (self.session == nil) {
//create peer picker and show picker of connections
GKPeerPickerController *peerPicker = [[GKPeerPickerController alloc] init];
peerPicker.delegate = self;
peerPicker.connectionTypesMask = GKPeerPickerConnectionTypeNearby;
[peerPicker show];
- (void)sendMessage:(id)sender
//package text field text as NSData object
NSData *textData = [self.messageToSendTextField.text dataUsingEncoding:NSASCIIStringEncoding];
//send data to all connected devices
[self.session sendDataToAllPeers:textData withDataMode:GKSendDataReliable error:nil];
- (GKSession *)peerPickerController:(GKPeerPickerController *)picker sessionForConnectionType:(GKPeerPickerConnectionType)type
//create ID for session
NSString *sessionIDString = @"MTBluetoothSessionID";
//create GKSession object
GKSession *session = [[GKSession alloc] initWithSessionID:sessionIDString displayName:nil sessionMode:GKSessionModePeer];
return session;
- (void)peerPickerController:(GKPeerPickerController *)picker didConnectPeer:(NSString *)peerID toSession:(GKSession *)session
//set session delegate and dismiss the picker
session.delegate = self;
self.session = session;
picker.delegate = nil;
[picker dismiss];
- (void)session:(GKSession *)session peer:(NSString *)peerID didChangeState:(GKPeerConnectionState)state
if (state == GKPeerStateConnected){
[session setDataReceiveHandler:self withContext:nil]; //set ViewController to receive data
self.sendButton.enabled = YES; //enable send button when session is connected
else {
self.sendButton.enabled = NO; //disable send button if session is disconnected
self.session.delegate = nil;
self.session = nil; //allow session to reconnect if it gets disconnected
- (void)receiveData:(NSData *)data fromPeer:(NSString *)peer inSession:(GKSession *)session context:(void *)context
//unpackage NSData to NSString and set incoming text as label's text
NSString *receivedString = [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];
self.messageReceivedLabel.text = receivedString;
- (void)viewDidLoad
[super viewDidLoad];
//Button to connect to other device
UIButton *connectButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
connectButton.frame = CGRectMake(20.0f, 20.0f, 80.0f, 40.0f);
[connectButton setTitle:@"Connect" forState:UIControlStateNormal];
connectButton.tintColor = [UIColor darkGrayColor];
[connectButton addTarget:self action:@selector(connectToDevice:) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:connectButton];
//Button to send message to other device
UIButton *sendButton_ = [UIButton buttonWithType:UIButtonTypeRoundedRect];
sendButton_.frame = CGRectMake(220.0f, 20.0f, 80.0f, 40.0f);
[sendButton_ setTitle:@"Send" forState:UIControlStateNormal];
sendButton_.tintColor = [UIColor darkGrayColor];
sendButton_.enabled = NO; //set button as disabled until connection is made
[sendButton_ addTarget:self action:@selector(sendMessage:) forControlEvents:UIControlEventTouchUpInside];
self.sendButton = sendButton_;
[self.view addSubview:self.sendButton];
//Label for message that is received
self.messageReceivedLabel = nil;
CGRect messageReceivedLabel_Frame = CGRectMake(20.0f, 80.0f, 280.0f, 44.0f);
UILabel *messageReceivedLabel_ = [[UILabel alloc] initWithFrame:messageReceivedLabel_Frame];
messageReceivedLabel_.textAlignment = UITextAlignmentCenter;
messageReceivedLabel_.font = [UIFont boldSystemFontOfSize:20.0f];
self.messageReceivedLabel = messageReceivedLabel_;
[self.view addSubview:self.messageReceivedLabel];
//Text field to input message to send
CGRect messageToSendTextField_Frame = CGRectMake(20.0f, 144.0f, 280.0f, 44.0f);
UITextField *messageToSendTextField_ = [[UITextField alloc] initWithFrame:messageToSendTextField_Frame];
messageToSendTextField_.font = [UIFont systemFontOfSize:20.0f];
messageToSendTextField_.backgroundColor = [UIColor whiteColor];
messageToSendTextField_.clearButtonMode = UITextFieldViewModeAlways;
messageToSendTextField_.placeholder = @"Enter a message to send";
messageToSendTextField_.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter;
self.messageToSendTextField = messageToSendTextField_;
[self.view addSubview:self.messageToSendTextField];
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
return (interfaceOrientation == UIInterfaceOrientationPortrait);

Step 8

Finally we click on the Run button to show the output.


Output 1 in iPhone:


Output 2 in iPhone:


Here we write a msg.

Output 3 in iPhone:


After clicking on the send button it searches for the device. But here it does not work because it is tested on the simulator.