Architecture-independent floor() function

swmath.m

/*
 * Calling math.h functions like `floor` and `floorf` on CGFloat variables
 * becomes problematic when compiling the same code for both 32-bit and 
 * 64-bit platforms, since CGFloat is double on 64-bit, float on 32-bit. 
 * Hence, if you compile with -Wconversion set, `floorf` will give a warning 
 * on 64-bit, while `floor` gives a warning on 32-bit.
 *
 * Here's a suggested implementation of an architecture-independent `floor` 
 * function, written using plain old function overloading which is enabled 
 * using the `__attribute__((overloadable))` Clang language extension.
 *
 * See http://clang.llvm.org/docs/LanguageExtensions.html#function-overloading-in-c
 */

float __attribute__((overloadable)) swfloor(float f) { return floorf(f); }
double __attribute__((overloadable)) swfloor(double d) { return floor(d); }

@implementation MyThingy

- (void)aMethod:(CGFloat)arg {
#pragma clang diagnostic push
#pragma clang diagnostic warning "-Wconversion"
    CGFloat flooredArg = swfloor(arg); // No warnings!
#pragma clang diagnostic pop
}

@end