The Plum-O-Meter: Weighing Plums Using 3D Touch in Swift | Hacker News Reader

The Plum-O-Meter: Weighing Plums Using 3D Touch in Swift

flexmonkey.blogspot.com

132 pointsNSFlexMonkey25 comments

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)

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.

If you put a very light balloon in there won't the air pressure increase more than a smaller but heavier apple?

You put the object ontop of the bag, not in it

Ah! That makes a lot more sense now...

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...

Cheers!

Wow, time to build one of these for drugs

Free GPS location tracker and opaque baseband processor included!

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.

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!

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.

A dollar bill weighs 1g.

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

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

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. :)

How about apples? Can you weigh apples?

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 :(

I had a similar idea for weighing pot, at least you dont need a scale.....

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.

Really? Lightly touch an icon but don't press hard enough to show the shortcut menu - as you modulate your touch pressure the glow will follow. When you peek an email, adjust the pressure of your touch - you will see it zoom in and out.

Within a few minutes of playing with the feature it was obvious that it was very high resolution detection of pressures.

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

https://medium.com/@rknla/exploring-apple-s-3d-touch-f5980ef...

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

I think this is the use case for a Bluetooth scale

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

If you stood on something acting as a lever that reduced the weight on your phone, you could probably make it work...

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