Mac Developer Library


Foundation Framework Reference NSNetServiceBrowser Class Reference

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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.