You can use `truncatingRemainder`

and `1`

as the divider.

Returns the remainder of this value divided by the given value using truncating division.

Apple doc

Example:

```
let myDouble1: Double = 12.25
let myDouble2: Double = 12.5
let myDouble3: Double = 12.75
let remainder1 = myDouble1.truncatingRemainder(dividingBy: 1)
let remainder2 = myDouble2.truncatingRemainder(dividingBy: 1)
let remainder3 = myDouble3.truncatingRemainder(dividingBy: 1)
remainder1 -> 0.25
remainder2 -> 0.5
remainder3 -> 0.75
```