Update: Apple have now defined some CGFloat-specific versions of common functions like ceil:
func ceil(x: CGFloat) -> CGFloat
…specifically to cope with the 32/64-bit difference. If you simply use ceil with a CGFloat argument it should now work on all architectures.
My original answer:
This is pretty horrible, I think, but can anyone think of a better way? #if doesn’t seem to work for CGFLOAT_IS_DOUBLE; I think you’re limited to build configurations, from what I can see in the documentation for conditional compilation.
var x = CGFloat(0.5)
#if arch(x86_64) || arch(arm64)
var test = ceil(x)
#else
var test = ceilf(x)
#endif