Apple always has an issue with sales slowdown when a new iPhone is in the wings, and that effect may have been magnified with this year’s model being the tenth anniversary special edition, expected in September. The company used that as a reason for its lacklustre fiscal second quarter, but that indicates a firm which is pinning far too many hopes on one device – even a special iPhone – and glossing over more endemic challenges like a slump in sales in China. In the quarter, revenues came in around $120m below Wall Street expectations at $52.9bn, largely because of a slip in iPhone sales. These were only down 1% year-on-year, but in Apple’s world that translates to 50.76m units,…