Design an "enhanced playback" feature for an audiobook app. For supported titles, the app has to show a specific image at set timestamps while the audio plays. How would you keep the audio clock and the image display in sync?
Use AVPlayer's boundary time observer (or a periodic observer plus binary search) to find the cue for the current time and show it, prefetching the next 1 or 2 images. On seek or rate change, recompute the active cue from the current position, and in the background stop image updates but resync by position on return.
iOS system designShort answerBasics
For a mobile feed, would you paginate by offset or by cursor (keyset)? Justify it with…
#prefetch
iOS system designShort answerAdvanced
The first screen is a grid of photo thumbnails from an API, and tapping one opens a…
#prefetch
iOS system designShort answerIntro
A travel booking app goes list → detail → booking. For each screen, how do you decide…
#prefetch
iOS system designShort answerAdvanced
Design a discovery screen full of thumbnail tiles, like Snapchat Discover. It scrolls…
#prefetch