Check if NSNumber is fraction

Question

What is the best way of checking if a NSNumber is a fraction?

NumberIsFraction(@(0)); // NO;
NumberIsFraction(@(0.5)); // YES;
NumberIsFraction(@(1.0)); // NO;

"Best" in terms of border case handling and performance.

Answer 1

Avoiding conversions to types with a smaller domain:

BOOL NumberIsFraction(NSNumber *number) {
    double dValue = [number doubleValue];
    if (dValue < 0.0)
        return (dValue != ceil(dValue));
    else
        return (dValue != floor(dValue));
}