They're almost certainly not storing a static list of numbers. As others have noted, they're using a UIPickerView. The delegate for that class has two methods that are particularly relevant for this, one that gets the value at "current row number" and one that says how many rows are in the model. The logic for the "current row" is almost certainly the normal modulo logic we're all familiar with. But since the component needs a "size" value for the data set, they pick something arbitrarily large on the (reasonable) assumption that no one will actually ever scroll that far unintentionally.

> They're almost certainly not storing a static list of numbers.

Probably. But I wouldn't bet on it. I once borrowed a car that would glitch if you pressed the cruise control buttons too fast. Normally + and - buttons increase and decrease the speed by 1 km/h. But if you do it too fast, it sometimes eats the entry, and starts skipping one position. Eg. it would increase from 105 to 107, and decrease from 107 to 105. It was persistent until cruise control was turned entirely off and on again. Eh? Making that bug must have taken more effort than doing it correctly. I guess it must be populating linked lists of possible speeds, and then screwing up the links when clicking too fast? (that was Jeep Renegade)

Applying this to answer the question directly -- no, this doesn't waste CPU cycles or memory because UIPickerView only keeps the visible rows in memory and generates them lazily as you scroll. Thus, the number of rows does not affect the performance of the picker.

All table- or list-like UI components across Apple's platforms work this way.