I am expecting the code below to cover the full Float range of which I use only a very small part just above 0.
My app however sometimes crashes in the field because it hits default: fatalError().
What could possibly be wrong here?
var value: Float // Between a little above 0 and about 15.
...
switch value
{
case ...3: return 0
case 3...10: return 1
case 10...: return 2
default: fatalError()
}
This switch will fall all the way through default for example if value is Float.nan or Float.signalingNaN, so it's technically possible for the app to legitimately crash at that point.
Consider adding some logging before crashing to check which value causes it to crash.
You have covered all cases except for the values whose eight exponent bits are all 1s. None of these are "Between a little above 0 and about 15", so your assumption is currently incorrect.
https://en.wikipedia.org/wiki/Single-precision_floating-point_format#Exponent_encoding