objective-c - Object-C 类内部不带加减号的方法是什么？代码如图。

typedef NS_ENUM(NSUInteger,BSDServerErrorCode) {
NOERROR,
SOCKETERROR,
BINDERROR,
LISTENERROR,
CFSOCKETCREATEERROR,
ACCEPTINGERROR
};

@interface BIDCFSocketServer : NSObject

@property (nonatomic)CFSocketRef sRef;
@property (nonatomic) int listenfd, errorCode;

-(instancetype)initOnPort:(int)port;

@end

 如下图代码所示的是.m文件；
"object-c
#define LISTENQ 1024
@implementation BIDCFSocketServer
-(instancetype)initOnPort:(int)port{
    struct sockaddr_in servaddr;
    CFRunLoopSourceRef source;
    const CFSocketContext context = {0,NULL,NULL,NULL,NULL};
    _errorCode = NOERROR;
    if((self.listenfd = socket(AF_INET,SOCK_STREAM,IPPROTO_TCP))<0) {
        _errorCode = NOERROR;
    }else{
        memset(&servaddr,0,sizeof servaddr);
        servaddr.sin_family = AF_INET;
        servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
        servaddr.sin_port = htons(port);
        if(bind(self.listenfd,(struct sockaddr*)&servaddr,sizeof(servaddr))<0) {
            _errorCode = BINDERROR;
        }else{
            if(listen(self.listenfd,LISTENQ)< 0){
                _errorCode = LISTENERROR;
            }else{
                self.sRef = CFSocketCreateWithNative(NULL,self.listenfd,kCFSocketAcceptCallBack,acceptConnection,&context);
                if(self.sRef == NULL) {
                    _errorCode = CFSOCKETCREATEERROR;
                }else{
                    source = CFSocketCreateRunLoopSource(kCFAllocatorDefault,self.sRef,0) ;
                    CFRunLoopAddSource(CFRunLoopGetCurrent(),source,kCFRunLoopDefaultMode);
                    CFRelease(source);
                    CFRunLoopRun();

                    }
                }
            }
        }
return self;
}
void acceptConnection(CFSocketRef sRef,CFSocketCallBackType cType,CFDataRef address,const void *data ,void * info) {
    CFSocketNativeHandle csock = *(CFSocketNativeHandle*)data;
    CFSocketRef sn;
    CFRunLoopSourceRef source;
    const CFSocketContext context = {0,NULL,NULL,NULL,NULL};

    sn = CFSocketCreateWithNative(NULL,csock,kCFSocketDataCallBack,receiveData,&context);
    source  = CFSocketCreateRunLoopSource(NULL,sn,0);
    CFRunLoopAddSource(CFRunLoopGetCurrent(),source,kCFRunLoopDefaultMode);
    CFRelease(source);
    CFRelease(sn);
    return;
}
void receiveData(CFSocketRef sRef,CFSocketCallBackType cType,CFDataRef address,const void * data,void *info) {
    CFDataRef df = (CFDataRef)data;
    long len = CFDataGetLength(df);
    if(len <= 0 )return ;
    UInt8 buf[len];
    CFRange range = CFRangeMake(0,len);
    CFDataGetBytes(df,range,buf);
    buf[len] = '\0';
    NSString * str = [[NSString alloc]initWithData:(__bridge NSData*)data encoding:NSASCIIStringEncoding];
    NSLog(@"Recieved: %@",str);
    [[NSNotificationCenter defaultCenter] postNotificationName:@"posttext" object:str];
    CFSocketSendData(sRef,address,df,0);//Echo back
}
@end

我想知道的是.m文件中的void acceptConnection(CFSocketRef sRef,CFSocketCallBackType cType,CFDataRef address,const void *data ,void * info) {...}是成员方法或者是是函数？其前面也没有加减号，以前从来么有见过。这东东是什么？能否补充下相关的知识，我的oc是自学的，求讲解下。谢谢各位大神！