The generational variety index (GVI) helps identify the components of product variants that are most likely to require redesign in the future. These components can then be embedded with the flexibility required for them to be easily modifiable; the remaining components can be designed into a platform. This paper describes the application of the GVI technique in studying the evolution of the Apple iPhone, which was first released in 2007 and has since undergone multiple redesigns. The analysis includes the five generations of the iPhone (original, 3G, 3GS, 4, and 4S) and focuses primarily on mechanical sub-systems. The results of the analysis and subsequent design recommendations are compared with the actual design evolution of the iPhone product line. For certain subsystems, this comparison reveals a divergence in Apple's design decision-making from the evolution recommended by the GVI technique. Limitations include its retrospective nature and the use of only publicly available data.