Find Mac OSX serial number

The following code is mainly copied from Technical Note TN1103, with small modifications to return an NSString and to make it compile with ARC:

#include <IOKit/IOKitLib.h>

- (NSString *)getSerialNumber
{
    NSString *serial = nil;
    io_service_t platformExpert = IOServiceGetMatchingService(kIOMasterPortDefault,
                                     IOServiceMatching("IOPlatformExpertDevice"));
    if (platformExpert) {
        CFTypeRef serialNumberAsCFString =
        IORegistryEntryCreateCFProperty(platformExpert,
                                        CFSTR(kIOPlatformSerialNumberKey),
                                        kCFAllocatorDefault, 0);
        if (serialNumberAsCFString) {
            serial = CFBridgingRelease(serialNumberAsCFString);
        }

        IOObjectRelease(platformExpert);
    }
    return serial;
}

You have to add the IOKit.framework to your build settings.

This is the Swift version of the solution:

var serialNumber: String? {
  let platformExpert = IOServiceGetMatchingService(kIOMasterPortDefault, IOServiceMatching("IOPlatformExpertDevice") )

  guard platformExpert > 0 else {
    return nil
  }

  guard let serialNumber = (IORegistryEntryCreateCFProperty(platformExpert, kIOPlatformSerialNumberKey as CFString, kCFAllocatorDefault, 0).takeUnretainedValue() as? String) else {
    return nil
  }


  IOObjectRelease(platformExpert)

  return serialNumber
}

This is a C++ version based on the TN1103 that Martin mention above.

C++ example:

#include <CoreFoundation/CoreFoundation.h>
#include <IOKit/IOKitLib.h>

std::string example_class::getSerialNumber()
{
    CFStringRef serial;
    char buffer[64] = {0};
    std::string seriaNumber("");
    io_service_t platformExpert = IOServiceGetMatchingService(kIOMasterPortDefault,
                                                          IOServiceMatching("IOPlatformExpertDevice"));
    if (platformExpert)
    {
        CFTypeRef serialNumberAsCFString = IORegistryEntryCreateCFProperty(platformExpert,
                                                                       CFSTR(kIOPlatformSerialNumberKey),
                                                                       kCFAllocatorDefault, 0);
        if (serialNumberAsCFString) {
            serial = (CFStringRef)serialNumberAsCFString;
        }
        if (CFStringGetCString(serial, buffer, 64, kCFStringEncodingUTF8)) {
            seriaNumber = buffer;
        }

        IOObjectRelease(platformExpert);
    }
    return seriaNumber;
}