Android - ConstraintLayout percentage using dimens
Instead of using a dimen resource, use an item resource of type dimen:
<item name="guideline_perc" type="dimen">0.5</item>
If using integers, an integer resource would work best:
<integer name="guideline_perc">1</integer>
To set a percentage use the fraction syntax
<fraction name="guideline_perc">0.5</fraction>and then
app:layout_constraintGuide_percent="@fraction/guideline_perc"
Now in 2021 dimen float works fine. Just autocompletion in Android studio in that case doesn't. Don't know why.
app:layout_constraintGuide_percent="@dimen/guideline_perc"