NSNetServiceBrowser Class Reference

Inherits from
Conforms to
Framework
/System/Library/Frameworks/Foundation.framework
Availability
Available in iOS 2.0 and later.
Declared in
NSNetServices.h
Companion guides
Related sample code

Overview

The NSNetServiceBrowser class defines an interface for finding published services on a network using multicast DNS. An instance of NSNetServiceBrowser is known as a network service browser.

Services can range from standard services, such as HTTP and FTP, to custom services defined by other applications. You can use a network service browser in your code to obtain the list of accessible domains and then to obtain an NSNetService object for each discovered service. Each network service browser performs one search at a time, so if you want to perform multiple simultaneous searches, use multiple network service browsers.

A network service browser performs all searches asynchronously using the current run loop to execute the search in the background. Results from a search are returned through the associated delegate object, which your client application must provide. Searching proceeds in the background until the object receives a stop message.

To use an NSNetServiceBrowser object to search for services, allocate it, initialize it, and assign a delegate. (If you wish, you can also use the scheduleInRunLoop:forMode: and removeFromRunLoop:forMode: methods to execute searches on a run loop other than the current one.) Once your object is ready, you begin by gathering the list of accessible domains using either the searchForRegistrationDomains or searchForBrowsableDomains methods. From the list of returned domains, you can pick one and use the searchForServicesOfType:inDomain: method to search for services in that domain.

The NSNetServiceBrowser class provides two ways to search for domains. In most cases, your client should use the searchForRegistrationDomains method to search only for local domains to which the host machine has registration authority. This is the preferred method for accessing domains as it guarantees that the host machine can connect to services in the returned domains. Access to domains outside this list may be more limited.

Tasks

Creating Network Service Browsers

Configuring Network Service Browsers

Using Network Service Browsers

Managing Run Loops

Properties

delegate

The delegate object for this instance.

@property (assign) id <NSNetServiceBrowserDelegate> delegate;
Availability
  • Available in iOS 2.0 and later.
Declared In
NSNetServices.h

Instance Methods

init

Initializes an allocated NSNetServiceBrowser object.

- (id)init
Return Value

Initialized NSNetServiceBrowser object.

Availability
  • Available in iOS 2.0 and later.
Declared In
NSNetServices.h

removeFromRunLoop:forMode:

Removes the receiver from the specified run loop.

- (void)removeFromRunLoop:(NSRunLoop *)runLoop forMode:(NSString *)runLoopMode
Parameters
runLoop

Run loop from which to remove the receiver.

runLoopMode

Run loop mode in which to perform this operation, such as NSDefaultRunLoopMode. See the Run Loop Modes section of the NSRunLoop class for other run loop mode values.

Discussion

You can use this method in conjunction with scheduleInRunLoop:forMode: to transfer the receiver to a run loop other than the default one. Although it is possible to remove an NSNetService object completely from any run loop and then attempt actions on it, you must not do it.

Availability
  • Available in iOS 2.0 and later.
Declared In
NSNetServices.h

scheduleInRunLoop:forMode:

Adds the receiver to the specified run loop.

- (void)scheduleInRunLoop:(NSRunLoop *)runLoop forMode:(NSString *)runLoopMode
Parameters
runLoop

Run loop in which to schedule the receiver.

runLoopMode

Run loop mode in which to perform this operation, such as NSDefaultRunLoopMode. See the Run Loop Modes section of the NSRunLoop class for other run loop mode values.

Discussion

You can use this method in conjunction with removeFromRunLoop:forMode: to transfer the receiver to a run loop other than the default one. You should not attempt to run the receiver on multiple run loops.

Availability
  • Available in iOS 2.0 and later.
Declared In
NSNetServices.h

searchForBrowsableDomains

Initiates a search for domains visible to the host. This method returns immediately.

- (void)searchForBrowsableDomains
Discussion

The delegate receives a netServiceBrowser:didFindDomain:moreComing: message for each domain discovered.

Availability
  • Available in iOS 2.0 and later.
Declared In
NSNetServices.h

searchForRegistrationDomains

Initiates a search for domains in which the host may register services.

- (void)searchForRegistrationDomains
Discussion

This method returns immediately, sending a netServiceBrowserWillSearch: message to the delegate if the network was ready to initiate the search. The delegate receives a subsequent netServiceBrowser:didFindDomain:moreComing: message for each domain discovered.

Most network service browser clients do not have to use this method—it is sufficient to publish a service with the empty string, which registers it in any available registration domains automatically.

Availability
  • Available in iOS 2.0 and later.
Declared In
NSNetServices.h

searchForServicesOfType:inDomain:

Starts a search for services of a particular type within a specific domain.

- (void)searchForServicesOfType:(NSString *)serviceType inDomain:(NSString *)domainName
Parameters
serviceType

Type of the service to search for.

domainName

Domain name in which to perform the search.

Discussion

This method returns immediately, sending a netServiceBrowserWillSearch: message to the delegate if the network was ready to initiate the search.The delegate receives subsequent netServiceBrowser:didFindService:moreComing: messages for each service discovered.

The serviceType argument must contain both the service type and transport layer information. To ensure that the mDNS responder searches for services, rather than hosts, make sure to prefix both the service name and transport layer name with an underscore character (“_”). For example, to search for an HTTP service on TCP, you would use the type string “_http._tcp.“. Note that the period character at the end is required.

The domainName argument can be an explicit domain name, the generic local domain @"local." (note trailing period, which indicates an absolute name), or the empty string (@""), which indicates the default registration domains. Usually, you pass in an empty string. Note that it is acceptable to use an empty string for the domainName argument when publishing or browsing a service, but do not rely on this for resolution.

Availability
  • Available in iOS 2.0 and later.
See Also
Declared In
NSNetServices.h

stop

Halts a currently running search or resolution.

- (void)stop
Discussion

This method sends a netServiceBrowserDidStopSearch: message to the delegate and causes the browser to discard any pending search results.

Availability
  • Available in iOS 2.0 and later.
See Also
Declared In
NSNetServices.h