Updating this since it’s been a while. We’re still leaving this as a possible future improvement. This is not a very popular feature on our website. Figuring out the design for mobile apps continues to be a challenge. Sorry for the inconvenience!Siggi Bjarna commented
iPhone user chiming in. I actually never noticed the "Itemized bill" or "Split by adjustment" options on the web app until today. I'm sorely disappointed I never noticed the "Split by adjustment" option as it is incredibly useful for me as ~80% of my entries are made this way.
I would really like to get the "Split by adjustment" feature into iOS, and I'll explain my workflow to show the benefit to me, and hopefully others!. I'll give a simple example of how I currently calculate the split amounts after some shopping for me and my roommate. This happens a dozen or more times each month.
Without "Split by adjustment": Bill total is $30; me $8, roommate $4, $18 remainder is split equally. Calculation steps: $30-$8-$4=$18/2=$9 each in common; then $9+$8=$17 for me and $9+$4=$13 for my flatmate. Then I enter the exact amounts into the new bill, snap a photo of the receipt and save the bill to Splitwise from my phone.
With "Split by adjustment": I would enter $30, enter a +$8 adjustment for me and +$4 for my roommate, snap a photo of the receipt and save the bill to Splitwise from my phone.
This is kind of long winded, but holy moly how much this would add to the user experience.
Whoops, we’re still considering this idea. It does sounds like a useful improvement in the add expense form.