NSNetServiceBrowsing无法解析服务，错误为72004

Question

几天来，我试图实现一个在网络中浏览Bonjour服务并在控制台中显示它们的应用程序(第一步(。我用NSNetServiceBrowser实现了一个类，并对它进行了初始化，如本文中的许多文章所示。但是在找到服务之后，我无法解析它以使主机名对我来说是可访问的。服务解析总是导致错误

-72004(NSNetServicesBadArgumentError(。

我试图使用@"local.">作为域或我的特定服务来查找，而不是使用>@"_services._dns-sd._udp.">

//
//  Bonjour.m
//  BonjourTest 
//
//  Created by PellePe on 21.07.18.
//  Copyright © 2018 PellePe. All rights reserved.
//
#import "Bonjour.h"
#import <Foundation/Foundation.h>
#include <netinet/in.h>

#define SERVICE_DOMAIN @"local"
#define SERVICE_TYPE   @"_bonjourTest._tcp"
#define SERVICE_NAME   @"Bonjour Test"
@interface Bonjour () <NSNetServiceDelegate, NSNetServiceBrowserDelegate>
@property (nonatomic, strong) NSMutableArray<NSNetService *> *detectedServices;
@property (nonatomic, strong) NSNetServiceBrowser *netServiceBrowser;
@end

@implementation Bonjour
#pragma mark -
#pragma mark Service Browsing
- (BOOL)isBrowsing {
return self.netServiceBrowser != NULL;
}
- (void)startServiceBrowsing:(NSString *)type {
if (self.detectedServices == NULL) {
self.detectedServices = [[NSMutableArray<NSNetService*> alloc] init];
} else {
[self.detectedServices removeAllObjects];
}
self.netServiceBrowser = [[NSNetServiceBrowser alloc] init];
self.netServiceBrowser.includesPeerToPeer = YES;
self.netServiceBrowser.delegate = self;
[self.netServiceBrowser searchForServicesOfType: type  // SERVICE_TYPE
inDomain: @""];
}
- (void)stopServiceBrowsing {
assert(self.netServiceBrowser != NULL);
[self.netServiceBrowser stop];
self.netServiceBrowser = NULL;
}
#pragma mark -
#pragma NSNetServiceDelegate
-(void)netServiceWillResolve:(NSNetService *)sender {
NSLog(@"netService will resolve - %@", sender.hostName);
}
- (void)netService:(NSNetService *)sender
didNotResolve:(NSDictionary<NSString *,NSNumber *> *)errorDict {
NSLog(@"netService did not resolve");
for (NSString *key in [errorDict allKeys]) {
NSLog(@"%@: %@", key, [errorDict objectForKey: key]);
}
}
- (void)netServiceDidResolveAddress:(NSNetService *)sender {
NSLog(@"netService did resolve address - %@", sender.hostName);  
}
#pragma mark -
#pragma mark NSNetServiceBrowserDelegate
- (void)netServiceBrowserWillSearch:(NSNetServiceBrowser *)browser {
NSLog(@"Browser will search");
}
- (void)netServiceBrowserDidStopSearch:(NSNetServiceBrowser *)browser {
NSLog(@"Browser did stop search");
}
- (void)netServiceBrowser:(NSNetServiceBrowser *)browser     didFindService:(NSNetService *)service moreComing:(BOOL)moreComing {
[self.detectedServices addObject: service];
service.delegate = self;
[service resolveWithTimeout: 100];
NSLog(@"Find service: %@ - %@ - %@ (%@)", service.name, service.hostName, service.type, moreComing ? @"YES" : @"No");
}
- (void)netServiceBrowser:(NSNetServiceBrowser *)browser didRemoveService:(NSNetService *)service moreComing:(BOOL)moreComing {
NSLog(@"Remove service: %@ - %@ - %@", service.name, service.hostName, service.type);
}
@end

我在网上搜索了好几个小时，但没有找到任何关于错误的提示-72004。使用NSNetServiceBrowser对如何初始化服务没有影响。

有人知道它出了什么问题吗？

Answer 1

所以这里的问题是，当你搜索_services._dns-sd._udp.时，你不会得到实际的服务，但你会得到所有类型的服务，例如。

let browser = NetServiceBrowser()
browser.searchForServices(ofType: "_googlecast._tcp", inDomain: "local")

此查询将返回类似于此的服务

NetService(domain: "local", type: "_googlecast._tcp", name: "RoomTV")

这是有效的，你可以毫无问题地解决，但当你像这样浏览时：

browser.searchForServices(ofType: "_services._dns-sd._udp.", inDomain: "local")

返回的服务将如下所示：

NetService(domain: ".", type: "_tcp.local.", name: "_googlecast")

因此，要解决此问题，您需要使用新类型再次搜索以获得实际服务。

let type = "(service.name).(service.type)"
.replacingOccurrences(of: "local.", with: "")
browser.searchForServices(ofType: type, inDomain: "local")