Apple's recent design revamp and Google's recent design revamp in their respective mobile platforms was not started by a 'design'. Apple and Google were collecting data and observing patterns in that data concerning User-Interfaces in-general. But where or how did they know to go to data and its collecting in user labs to get the new design approaches?
It happens to involve a certain philosophy revolution in the 9th century that affected every hard and soft science known to mankind. CI Lewis in the early in 19th century came up with a theory of knowledge, in his work titled..Mind and the World Order.
Basically, we can gain knowledge of how the world works by examining data and patterns in data. In the Mobile User-Interface context we are re-organizing data for a smaller screen size and other factors that demand that we cast the UI into a new form that is easier for humans to grasp and use right waya without an instructional manual.
Even with International Design(Swiss Design) it was based on some new human knowledge of how our brains work and how our eyes work and transforming that new knowledge which had some new data and patterns basis into a new design process. No-one realizes that all that data and its patterns are somewhat engineering based, not design based.
We keep hearing start-ups and other firms make the same mobile developer mistake of insisting with the lack of senior developers around that its the one-app portfolio of visually stunning ap that indicates the mobile developer needed when in fact according to both Apple and Google within their own hiring funnels its in fact the strong engineering software engineer that happens to do mobile applications that is in fact the choice that should be made.
Or to put another way, the short-term gain in getting that visual stunning one-mobile app-portfolio mobile developer is soon displaced by a medium-to-long-range loss in that the strong software engineering skills are not there to plot a long-term course of successful additions to that mobile application and surrounding services it uses.
Engineering in its practices of data collection and data analysis to determine patterns drives design not the other way around.