errors in Sending email in iPhone

Programming for iPhone: errors in Sending email in iPhone on newest questions tagged iphone – Stack Overflow

I’m trying to create application that sends email
I used classes like
SKPSMTPMessage , NSStream+SKPSMTPExtensions, NSData+Base64Additions, HSK_CFUtilities, Base64Transcoder
but it gives me the following errors

Undefined symbols for architecture i386:
"_OBJC_CLASS_$_SKPSMTPMessage", referenced from:
  objc-class-ref in MFViewController.o
"_kSKPSMTPPartContentTransferEncodingKey", referenced from:
  -[MFViewController sendMail:] in MFViewController.o
"_kSKPSMTPPartContentTypeKey", referenced from:
  -[MFViewController sendMail:] in MFViewController.o
"_kSKPSMTPPartMessageKey", referenced from:
  -[MFViewController sendMail:] in MFViewController.o
"_CFHostCreateWithName", referenced from:
  +[NSStream(SKPSMTPExtensions) getStreamsToHostNamed:port:inputStream:outputStream:] in    NSStream+SKPSMTPExtensions.o
  +[NSStream(SKPSMTPExtensions) getStreamsToHostNamed:port:inputStream:outputStream:] in  SKPSMTPMessage.o
"_CFStreamCreatePairWithSocketToCFHost", referenced from:
  +[NSStream(SKPSMTPExtensions) getStreamsToHostNamed:port:inputStream:outputStream:] in NSStream+SKPSMTPExtensions.o
  +[NSStream(SKPSMTPExtensions) getStreamsToHostNamed:port:inputStream:outputStream:] in SKPSMTPMessage.o
 ld: symbol(s) not found for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see invocation)

keep in mind that I’m using Xcode 4.3 ,
what shall I do to solve this??

After adding the CFNetwork framework and SystemConfiguration framework ,
the number of errors decreased from 6 to 4 and it is now

Undefined symbols for architecture i386:
"_OBJC_CLASS_$_SKPSMTPMessage", referenced from:
  objc-class-ref in MFViewController.o
"_kSKPSMTPPartContentTransferEncodingKey", referenced from:
  -[MFViewController sendMail:] in MFViewController.o
"_kSKPSMTPPartContentTypeKey", referenced from:
  -[MFViewController sendMail:] in MFViewController.o
"_kSKPSMTPPartMessageKey", referenced from:
  -[MFViewController sendMail:] in MFViewController.o
ld: symbol(s) not found for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see invocation)

source: http://stackoverflow.com/questions/10436521/errors-in-sending-email-in-iphone
Programming for iPhone: programming-for-iphone