A CFStreamError is defined as the following :

typedef struct { CFStreamErrorDomain domain; SInt32 error } CFStreamError;

But when you get such an error, you only get a domain code and an error code, which doesn’t really mean anything. To make it human readable, you need to compare the domain to all the existing domain constants :

CFStreamError error; if (error.error != 0) { if (error.domain == kCFStreamErrorDomainPOSIX) { NSLog(@”POSIX error domain, CFSTream.h says error code is to be interpreted using sys/errno.h.”); } else if (error.domain == kCFStreamErrorDomainMacOSStatus) { OSStatus macError = (OSStatus)error.error; NSLog(@”OS error: %d, CFStream.h says error code is to be interpreted using MacTypes.h.”, macError); } else if (error.domain == kCFStreamErrorDomainHTTP) { NSLog(@”HTTP error domain, CFHTTPSteam.h says error code is the HTTP error code.”); } else if (error.domain == kCFStreamErrorDomainMach) { NSLog(@”Mach error domain, CFNetServices.h says error code is to be interpreted using mach/error.h.”); } else if (error.domain == kCFStreamErrorDomainNetDB) { NSLog(@”NetDB error domain, CFHTTPHost.h says error code is to be finterpreted using netdb.h.”); } else if (error.domain == kCFStreamErrorDomainCustom) { NSLog(@”Custom error domain”); } else if (error.domain == kCFStreamErrorDomainSystemConfiguration) { NSLog(@”System Configuration error domain, CFHost.h says error code is to be interpreted using SystemConfiguration/SystemConfiguration.h.”); } NSLog(@”error %d domain %d”, error.error, error.domain); }

Once you have the domain, look at the corresponding header file to get the error description.

(Thanks http://www.cocoabuilder.com/archive/message/cocoa/2004/9/15/117526 and http://www.sporkstorms.org/code/DAClient/DAClient.m)