The security level of the target stream. May be one of the following values: NSStreamSocketSecurityLevelNone, NSStreamSocketSecurityLevelSSLv2, NSStreamSocketSecurityLevelSSLv3, NSStreamSocketSecurityLevelTLSv1, or NSStreamSocketSecurityLevelNegotiatedSSL.
Available in Mac OS X v10.3 and later.
Declaration Syntax Version Information- Available in Monobjc Bridge: 10.6 (For Mac OS X 10.6 and later), 10.5 (For Mac OS X 10.5 and later)