Swift OS X: get MAC address for en0

getMACAddress.swift

/ Returns an iterator containing the primary (built-in) Ethernet interface. The caller is responsible for
// releasing the iterator after the caller is done with it.
func FindEthernetInterfaces() -> io_iterator_t? {
    
    let matchingDictUM = IOServiceMatching("IOEthernetInterface");
    // Note that another option here would be:
    // matchingDict = IOBSDMatching("en0");
    // but en0: isn't necessarily the primary interface, especially on systems with multiple Ethernet ports.
    
    if matchingDictUM == nil {
        return nil
    }
    let matchingDict = matchingDictUM as NSMutableDictionary
    matchingDict["IOPropertyMatch"] = [ "IOPrimaryInterface" : true]
    
    var matchingServices : io_iterator_t = 0
    if IOServiceGetMatchingServices(kIOMasterPortDefault, matchingDict, &matchingServices) != KERN_SUCCESS {
        return nil
    }
    
    return matchingServices
}

// Given an iterator across a set of Ethernet interfaces, return the MAC address of the last one.
// If no interfaces are found the MAC address is set to an empty string.
// In this sample the iterator should contain just the primary interface.
func GetMACAddress(intfIterator : io_iterator_t) -> [UInt8]? {
    
    var macAddress : [UInt8]?
    
    var intfService = IOIteratorNext(intfIterator)
    while intfService != 0 {
        
        var controllerService : io_object_t = 0
        if IORegistryEntryGetParentEntry(intfService, "IOService", &controllerService) == KERN_SUCCESS {
            
            let dataUM = IORegistryEntryCreateCFProperty(controllerService, "IOMACAddress", kCFAllocatorDefault, 0)
            if dataUM != nil {
                let data = dataUM.takeRetainedValue() as! NSData
                macAddress = [0, 0, 0, 0, 0, 0]
                data.getBytes(&macAddress!, length: macAddress!.count)
            }
            IOObjectRelease(controllerService)
        }
        
        IOObjectRelease(intfService)
        intfService = IOIteratorNext(intfIterator)
    }
    
    return macAddress
}


if let intfIterator = FindEthernetInterfaces() {
    if let macAddress = GetMACAddress(intfIterator) {
        let macAddressAsString = macAddress.map( { String(format:"%02x", $0) } ).joinWithSeparator(":")
        print(macAddressAsString)
    }
    
    IOObjectRelease(intfIterator)
}