[HN Gopher] Why the iPhone Timer App displays a Fake Time
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Why the iPhone Timer App displays a Fake Time
Author : _antix
Score : 58 points
Date : 2020-12-28 21:56 UTC (1 hours ago)
(HTM) web link (lukashermann.dev)
(TXT) w3m dump (lukashermann.dev)
| jewel wrote:
| From what I can see, the iPhone timer app is rounding to the
| nearest second. For positive numbers that can be accomplished
| with either Math.round(t) or Math.floor(t+0.5).
| jrockway wrote:
| I think I find the ceiling method most intuitive. I have noticed
| that video games with cooldowns tend to agree with me; some
| ability has a 4 second cooldown, you press it, and the UI says
| "4", even though 3.999 seconds remain until the ability is back.
| (This means that you never see "0"; the counter reads "1" for the
| last second before the cooldown is available again.)
| tantalor wrote:
| Answer: it rounds to the nearest second.
| tobr wrote:
| > But for a countdown timer, this is counterintuitive.
|
| I get the feeling this pun wasn't intentional, but it's a good
| one nonetheless.
| dan-robertson wrote:
| ... or they just round the time to the nearest second instead of
| taking the floor
| nemetroid wrote:
| I think "rounds to closest" is a simpler way to put it than "adds
| 500 ms before truncating".
| sokoloff wrote:
| > Milliseconds are converted to seconds by dividing by 1000 and
| rounding down like so
|
| It seems like the simpler explanation is that the iPhone actually
| rounds to the closest integer rather than rounding down. (Whether
| they do this invisibly by adding 0.5s and rounding down is an
| implementation detail.)
| tobr wrote:
| Agreed, to my eyes it seems clear that the display shows both
| "5" and "0" for half a second, which means the total duration
| is still 5 seconds, not 5.5 seconds.
| jiofih wrote:
| The sentence quoted is for the first example in the post, not
| the iPhone timer.
|
| That's most likely what it does indeed, much more elegant than
| keeping track of the extra 500ms.
| sokoloff wrote:
| I realize that. It seems like the entire blog post could be
| summarized as "I thought about doing something this way and
| when it didn't give me what I and everyone else expects out
| of a timer, my mental model adjusted to conclude that Apple
| was doing some weird gymnastics involving adding 500ms to
| some of their timer code and using Math.floor() but not to
| the time the timer actually goes off rather than adjusting my
| mental model to match the simpler way that humans expect
| rounding to work in a timer using [the equivalent of]
| Math.round()."
| stevage wrote:
| Very weird to frame this as "lying" and "fake" when it's just
| using .round() instead of .floor()
| mgkimsal wrote:
| iOS 9 and below, IIRC, the timer app stopwatch screen would
| really flake out after 1000 hours. By 'flake out' I mean it would
| slow down the updating a lot - screen got somewhat jerky and slow
| to respond.
|
| From iOS 10 onwards, 1000+ hours doesn't seem to phase it at all
| - no slow downs.
|
| source: 1490:43:24 ago I started my timer, but I can't remember
| why now.
| arthurofbabylon wrote:
| While building a tea timer I naturally stumbled into this exact
| solution.
|
| Edit: sencha.app for those curious
| [deleted]
| kivlad wrote:
| This gives me a nostalgic reminder of when I used to watch
| Nickelodeon GUTS. Whenever a countdown timed challenge was about
| to end, I would hear the audience count down starting with "10"
| at maybe 10.7 seconds, "9" at 9.7 seconds, etc. Then after "1",
| there was a small period of awkward silence and murmurs from the
| audience before the siren blasted.
|
| It's a good example of how measurement of time in terms of human
| perception differs from the pure mathematical sense, and rounding
| is a good compromise here (wherever it doesn't display fractional
| seconds).
| mey wrote:
| Round half up is the typical expectation for most people in
| rounding to the nearest whole value.
|
| It isn't displaying a "fake" time, it's rounding.
|
| https://en.wikipedia.org/wiki/Rounding#Round_half_up
|
| Edit: Note, Round Half Up != Round half away from zero but that
| isn't important for this scenario :D
| chrisseaton wrote:
| I think my Garmin smartwatch shows distance rounded up, but plays
| alerts based on the actual value. So you can have run a watch
| that says you've run 10.00 km on the display... but have to go a
| bit further to trigger the 10 km vibration alarm. And crucially
| if you stopped before the alarm it wouldn't register as a 10 km
| for your records!
| vthommeret wrote:
| I built a similar tool to the OP that implements the same
| rounding behavior if you're in the iOS ecosystem --
| https://apps.apple.com/us/app/synctimer-by-practice/id152297...
|
| One of the main benefits is that it doesn't require the internet
| and can synchronize iPhones, iPads, and Apple TV's using either
| peer-to-peer WiFi or Bluetooth with no manual pairing.
|
| Also had an interval timer for exercises, group activities,
| etc...
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(page generated 2020-12-28 23:00 UTC)