ViewController.m

//
//  ViewController.m
//  LIFX
//
//  Created by Gary Riches on 18/01/2016.
//  Copyright © 2016 Gary Riches. All rights reserved.
//

#import "ViewController.h"
#import "GCDAsyncUdpSocket.h"

typedef struct {
	/* frame */
	uint16_t size;
	uint16_t protocol:12;
	uint8_t  addressable:1;
	uint8_t  tagged:1;
	uint8_t  origin:2;
	uint32_t source;
	/* frame address */
	uint8_t  target[8];
	uint8_t  reserved[6];
	uint8_t  res_required:1;
	uint8_t  ack_required:1;
	uint8_t  :6;
	uint8_t  sequence;
	/* protocol header */
	uint64_t :64;
	uint16_t type;
	uint16_t reserved_header:16;
	/* variable length payload follows */
} packet;


packet CreatePacket(){
	packet Packet;

	return Packet;
}

@interface ViewController () <GCDAsyncUdpSocketDelegate>

@property (nonatomic, strong) GCDAsyncUdpSocket *udpSocket;

@end

@implementation ViewController

- (void)viewDidLoad {
	[super viewDidLoad];
	// Do any additional setup after loading the view, typically from a nib.
	
	self.udpSocket = [[GCDAsyncUdpSocket alloc] initWithDelegate:self delegateQueue:dispatch_get_main_queue()];
	self.udpSocket.delegate = self;
	
	// Discover
	[self discover];
}

- (void)udpSocket:(GCDAsyncUdpSocket *)sock didReceiveData:(NSData *)data fromAddress:(NSData *)address withFilterContext:(id)filterContext {
	
	NSString *response = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
	NSLog(@"%@", response);
}

- (void)discover {
	
	[self.udpSocket enableBroadcast:YES error:nil];
	self.udpSocket.delegate = self;
	[self.udpSocket bindToPort:56700 error:nil];
	[self.udpSocket beginReceiving:nil];

	[self findBulbs];
	
	[self performSelector:@selector(cancelFindBulbs) withObject:nil afterDelay:12];
}

- (void)findBulbs
{
	packet discovery = CreatePacket();
	
	discovery.protocol = 1024;
	discovery.addressable = 1;
	discovery.tagged = 1;
	discovery.origin = 0;
	discovery.source = 0;
	
	bzero(discovery.target, sizeof(discovery.target));
	bzero(discovery.reserved, sizeof(discovery.reserved));
	discovery.res_required = 0;
	discovery.ack_required = 0;
	discovery.sequence = 0;
	discovery.reserved_header = 0;
	discovery.type = 2;
	
	discovery.size = sizeof(discovery);
	
	NSData *bytes = [NSData dataWithBytes:&discovery length:sizeof(discovery)];
	
	[self.udpSocket sendData:bytes toHost:@"255.255.255.255" port:56700 withTimeout:-1 tag:1];
	[self performSelector:@selector(findBulbs) withObject:nil afterDelay:1];
}

- (void)cancelFindBulbs
{
	[self.udpSocket pauseReceiving];
	[self.udpSocket enableBroadcast:NO error:nil];
}

@end