I ran into the problem the other day of having to encode a string using CP037 encoding, to communicate with the server. This turned out to be tricky than I had hoped because CP037 is not in the NSStringEncoding enum list of encoding directly supported by NSString.
I did managed to find support for CP037 in CFStringEncodingExt as kCFStringEncodingEBCDIC_CP037. I know that NSString and CFString toll-free bridged data types so all I had to do was encode my NSString using CFString encoding and I would have the value that I needed to send to the server.
NSString *stringThatNeedsToBeEncoded = @"randomString"; CFDataRef encodedStringAsCFData = CFStringCreateExternalRepresentation(CFAllocatorGetDefault(), (CFStringRef)stringThatNeedsToBeEncoded, kCFStringEncodingEBCDIC_CP037, 0); CFIndex bufferLength = CFDataGetLength(encodedStringAsCFData); UInt8 *buffer = malloc(bufferLength); CFDataGetBytes(encodedStringAsCFData, CFRangeMake(0, CFDataGetLength(encodedStringAsCFData)), buffer);
And inside buffer I had my byte array which I needed.