How to in calculate percentages in swift?

Question

I am creating an expense ios application. I am using a Progress View to display how much income the user has left. So for example, if the user puts $100 income, and $30 expense, I'd like the bar to be 70% full. How do I calculate this?

I had originally put

let fractionalProgress = Float(expenseFloat!)/Float(balanceFloat!)

but this doesn't return the right value needed.

Answer 1

The formula in your question is correct if you want to know the percentage spent so far.

The percent remaining formula is "remaining balance" / "original balance".

And of course "remaining balance" is "original balance" - "total of expenses".

let fractionalProgress = (balanceFloat - expenseFloat) / balanceFloat

where balanceFloat is the original balance and expenseFloat is the total expenses.

In your example with a balanceFloat of 100 and an expenseFloat of 30 this gives (100 - 30) / 100 which is 0.7.

Of course you would multiple this result by 100 if you wish to show a percentage. Better yet, use a NumberFormatter setup with a .percent style.