NSXMLParar para um valor de tag específico

Tenho um arquivo XML parecido com este:

 <country>
            <routes>
                <SourceCountry>Ireland</SourceCountry>
                <SourcePort>Larne</SourcePort>
                <DestinationCountry>UK</DestinationCountry>
                <DestinationPort>Troon </DestinationPort>
                        </routes>
            <routes>
                <SourceCountry>Ireland</SourceCountry>
                <SourcePort>Larne</SourcePort>
                <DestinationCountry>UK</DestinationCountry>
                <DestinationPort>Cairnryan </DestinationPort>
                        </routes>
            <routes>
                <SourceCountry>Ireland</SourceCountry>
                <SourcePort>Belfast</SourcePort>
                <DestinationCountry>UK</DestinationCountry>
                <DestinationPort>Birkenhead </DestinationPort>
                        </routes>
            <routes>
                <SourceCountry>Ireland</SourceCountry>
                <SourcePort>Belfast</SourcePort>
                <DestinationCountry>Belgium</DestinationCountry>
                <DestinationPort>Heysham </DestinationPort>
                        </routes>
            <routes>
                <SourceCountry>Belgium</SourceCountry>
                <SourcePort>Warrenpoint</SourcePort>
                <DestinationCountry>UK</DestinationCountry>
                <DestinationPort>Heysham </DestinationPort>
                        </routes>

Quero analisar dados específicos para<SourceCountry> == Ireland and <DestinationCountry> == UK. Como posso fazer isso

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