
The Plum-O-Meter: Weighing Plums Using 3D Touch in Swift - NSFlexMonkey
http://flexmonkey.blogspot.com/2015/10/the-plum-o-meter-weighing-plums-using.html
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cryptoz
That's awesome. You can make a scale another way too, by using the barometer
in the iPhone. You will need a ziplock or other airtight clear plastic bag,
and an object of known weight for calibration.

You can measure the change in air pressure in the bag with your iPhone inside,
and put your object to weigh on top of the bag (carefully balanced). There is
a linear relationship between the rise in air pressure and the weight of the
object on the bag (I tried this and it does work)

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userbinator
Note that the bag must be extremely flexible for that to work. Otherwise the
weight will be supported by the bag and the air pressure inside will be lower.

For some reason, that reminds me of the classic "measure the height of a
building using a barometer" joke.

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NSFlexMonkey
If you enjoyed that, I have a shed load of other 3D Touch experiments written
in Swift targeting the iPhone 6s:

[http://flexmonkey.blogspot.co.uk/2015/10/3d-touch-in-
swift-r...](http://flexmonkey.blogspot.co.uk/2015/10/3d-touch-in-swift-
retrospective.html)

Cheers!

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longlivegnu
Wow, time to build one of these for drugs

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walterbell
Free GPS location tracker and opaque baseband processor included!

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seivan
So when can you weigh a dime bag? Asking for a friend. But seriously this
could be potentially awesome.

Could you convince people to put a bowl on their phone, memorise its "weight"
and then fill it with stuff to calculate calories. Replacing those digital
food scales.

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NSFlexMonkey
I've only tinkered so far, but I've just ordered a set of calibration weights
to have a proper play next week.

Watch this space!

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thrownaway2424
A US nickel coin weighs exactly 5g.

Edit: if you happen to be in that exotic locale. I'm sure other coinage has
similarly consistent weight.

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weaksauce
A dollar bill weighs 1g.

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thrownaway2424
That's cool. I assume that holds for any American bill, since they're all the
same size?

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weaksauce
indeed it does. I have done it with 10 bills of mixed denominations and it's
10 grams on a scale.

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matheweis
Ah, you beat me to it; I was just talking with my coworkers about something
like this as a fun application of the new 3D touch. We were theorizing that a
~100g capacitive tray could be used to enable the capacitive touch; then use
that as the zero reference and weigh things in the tray. :)

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spython
How about apples? Can you weigh apples?

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NSFlexMonkey
I think apples will work. Grapes were my plan, because I could fit five on the
screen. Sadly the little blighters weren't heavy enough to make it work :(

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vitalus
What kind of granularity can you get with this? Based on all of the apps/build
in features utilizing 3D Touch, I had thought it was binary.

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porsupah
Somewhere around 336 levels, it would seem, with this generation.

[https://medium.com/@rknla/exploring-
apple-s-3d-touch-f5980ef...](https://medium.com/@rknla/exploring-
apple-s-3d-touch-f5980ef45af5)

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GPGPU
It would be great if I can step on my iPhone every morning, and MyFitnessPal
would record my weight.

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jschwartzi
I think this is the use case for a Bluetooth scale

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GPGPU
Yeah, but I'm not going to take a Bluetooth scale when I go on business trips.

