Easy Bonjour Browsing

example.m

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    // other code here...

    [[RBServerLocator sharedLocator] locateServerMatchingType:@"_myapp._tcp"
                                                   completion:^(NSNetService *service) {
                                                       NSLog(@"found server: %@", [service RBResolvedURL]);
                                                   }];

    
    // other code here...
}

RBServerLocator.h

//
//  RBServerLocator.h
//
//  Created by Justin Voss on 12/9/11.
//

#import <Foundation/Foundation.h>

@interface RBServerLocator : NSObject <NSNetServiceBrowserDelegate, NSNetServiceDelegate>
{
    void (^__completion_block)(NSNetService *);
    NSMutableArray *__foundServices;
}

@property (strong, nonatomic) NSNetServiceBrowser *serviceBrowser;

+ (RBServerLocator *)sharedLocator;

- (void)locateServerMatchingType:(NSString *)type completion:(void (^)(NSNetService *))completionBlock;

@end


@interface NSNetService (RBResolvedURL)
- (NSURL *)RBResolvedURL;
@end

RBServerLocator.m

//
//  RBServerLocator.m
//
//  Created by Justin Voss on 12/9/11.
//

#import "RBServerLocator.h"

@interface RBServerLocator (Private)
- (void)resolveFirstService;
@end

@implementation RBServerLocator

@synthesize serviceBrowser = _serviceBrowser;

+ (RBServerLocator *)sharedLocator
{
    static RBServerLocator *sharedLocator;
    
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        sharedLocator = [RBServerLocator new];
    });
    
    return sharedLocator;
}

- (id)init
{
    self = [super init];
    if (self) {
        self.serviceBrowser = [NSNetServiceBrowser new];
        self.serviceBrowser.delegate = self;
        __foundServices = [NSMutableArray array];
    }
    return self;
}

- (void)locateServerMatchingType:(NSString *)type completion:(void (^)(NSNetService *))completionBlock
{
    [__foundServices removeAllObjects];
    if (completionBlock) {
        __completion_block = completionBlock;
    }
    
    [self.serviceBrowser searchForServicesOfType:type inDomain:@""];
}

#pragma mark - Service Browsing

- (void)netServiceBrowser:(NSNetServiceBrowser *)aNetServiceBrowser didFindService:(NSNetService *)aNetService moreComing:(BOOL)moreComing
{
    [__foundServices addObject:aNetService];
    
    if (!moreComing) {
        [self resolveFirstService];
    }
}

#pragma mark - Service Resolving

- (void)resolveFirstService
{
    NSNetService *service = [__foundServices objectAtIndex:0];
    service.delegate = self;
    [service resolveWithTimeout:10.0];
}

- (void)netServiceDidResolveAddress:(NSNetService *)sender
{
    if (__completion_block) {
        __completion_block(sender);
    }
    
    __completion_block = NULL;
}

@end


@implementation NSNetService (RBResolvedURL)

- (NSURL *)RBResolvedURL
{
    return [NSURL URLWithString:[NSString stringWithFormat:@"http://%@:%d/", self.hostName, self.port]];
}

@end