You probably don't need to tell me that this is a bad idea.

sillyloop.m

#import <Foundation/Foundation.h>

typedef NS_ENUM(int, GJLRangeDirection) {
    GJLRangeDirectionPositive,
    GJLRangeDirectionNegative,
};

@interface GJLRange : NSEnumerator

+ (instancetype)rangeWithStart: (NSNumber *)start end: (NSNumber *)end step: (NSNumber *)step;

@end

@implementation GJLRange
{
    double _start;
    double _end;
    double _step;
    double _cursor;
    GJLRangeDirection _direction;
}

+ (instancetype)rangeWithStart: (NSNumber *)start end: (NSNumber *)end step: (NSNumber *)step
{
    NSParameterAssert(start != end);
    NSParameterAssert(step != 0);
    GJLRange *range = [self new];
    range->_start = [start doubleValue];
    range->_end = [end doubleValue];
    range->_step = [step doubleValue];
    if ([step compare:@0] == NSOrderedAscending) {
        range->_direction = GJLRangeDirectionNegative;
        NSParameterAssert(range->_start > range->_end);
    } else {
        range->_direction = GJLRangeDirectionPositive;
        NSParameterAssert(range->_start < range->_end);
    }
    range->_cursor = range->_start;
    return range;
}

- (BOOL)isStillGoing
{
    switch (_direction) {
        case GJLRangeDirectionPositive:
            return _cursor - _end < _step;
        case GJLRangeDirectionNegative:
            return _cursor - _end > _step;
    }
}

- (id)nextObject
{
    if (![self isStillGoing]) {
        return nil;
    }
    NSNumber *result = @(_cursor);
    _cursor += _step;
    return result;
}

@end

@interface NSNumber (GJLRange)

- (id <NSFastEnumeration>)to:(NSNumber *)destination by:(NSNumber *)step;
- (id <NSFastEnumeration>)to:(NSNumber *)destination;

@end

@implementation NSNumber (GJLRange)

- (id <NSFastEnumeration>)to:(NSNumber *)destination by:(NSNumber *)step
{
    return [GJLRange rangeWithStart: self end: destination step: step];
}

- (id <NSFastEnumeration>)to:(NSNumber *)destination
{
    return [self to:destination by: ([self compare:destination] == NSOrderedAscending)?@1:@(-1)];
}

@end

int main(int argc, const char * argv[])
{
    @autoreleasepool {
        for (id bottleCount in [@10 to: @1]) {
            printf("%d green bottles, hanging on the wall...\n", [bottleCount intValue]);
        }
    }
}

sillyloop2.m

#import <Foundation/Foundation.h>

typedef NS_ENUM(int, GJLRangeDirection) {
    GJLRangeDirectionPositive,
    GJLRangeDirectionNegative,
};

@interface GJLRange : NSEnumerator

+ (instancetype)rangeWithStart: (NSNumber *)start end: (NSNumber *)end step: (NSNumber *)step;

@end

@implementation GJLRange
{
    double _start;
    double _end;
    double _step;
    int _index;
    GJLRangeDirection _direction;
}

+ (instancetype)rangeWithStart: (NSNumber *)start end: (NSNumber *)end step: (NSNumber *)step
{
    NSParameterAssert(start != end);
    NSParameterAssert(step != 0);
    GJLRange *range = [self new];
    range->_start = [start doubleValue];
    range->_end = [end doubleValue];
    range->_step = [step doubleValue];
    if ([step compare:@0] == NSOrderedAscending) {
        range->_direction = GJLRangeDirectionNegative;
        NSParameterAssert(range->_start > range->_end);
    } else {
        range->_direction = GJLRangeDirectionPositive;
        NSParameterAssert(range->_start < range->_end);
    }
    return range;
}

- (id)objectAtIndexedSubscript:(NSUInteger)index
{
    return @(_start + (_index * _step));
}

- (BOOL)isStillGoing:(NSNumber *)currentValue
{
    switch (_direction) {
        case GJLRangeDirectionPositive:
            return [currentValue doubleValue] - _end < _step;
        case GJLRangeDirectionNegative:
            return [currentValue doubleValue] - _end > _step;
    }
}

- (id)nextObject
{
    NSNumber *result = self[_index];
    if (![self isStillGoing:result]) {
        return nil;
    }
    _index += 1;
    return result;
}

@end

@interface NSNumber (GJLRange)

- (id <NSFastEnumeration>)to:(NSNumber *)destination by:(NSNumber *)step;
- (id <NSFastEnumeration>)to:(NSNumber *)destination;

@end

@implementation NSNumber (GJLRange)

- (id <NSFastEnumeration>)to:(NSNumber *)destination by:(NSNumber *)step
{
    return [GJLRange rangeWithStart: self end: destination step: step];
}

- (id <NSFastEnumeration>)to:(NSNumber *)destination
{
    return [self to:destination by: ([self compare:destination] == NSOrderedAscending)?@1:@(-1)];
}

@end

int main(int argc, const char * argv[])
{
    @autoreleasepool {
        for (id bottleCount in [@10 to: @1]) {
            printf("%d green bottles, hanging on the wall...\n", [bottleCount intValue]);
        }
    }
}

The second, only marginally less over-engineered solution was suggested by David Ronnqvist.