[iOS] How to get Storage Available

how to get storage available

-(NSNumber *)getStorageAvailable
{
    NSNumber *availableGiga = [NsNumber numberWithFloat:0.0f];
    NSError *error = nil;
    NSArray *paths = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSDictionary *dictionary = [[NSFileManager defaultManager] attributesOfFileSystemForPath:[paths lastObject] error:&error];
    // 소수 2자리까지 표시
    NSNumberFormatter *formatter = [[NSNumberFormatter alloc] init];
    formatter.roundingIncrement = [NSNumber numberWithFloat:0.01];
    formatter.numberStyle = NSNumberFormatterDecimalStyle;

    if (dictionary) {
        NSNumber *availableByte = [dictionary objectForKey:NSFileSystemFreeSize];
        availableGiga = [NSNumber numberWithFloat:((([availableByte floatValue] / 1024) / 1024) / 1024)];
        NSLog(@"%@G", [formatter stringFromNumber:availableGiga]);
    } else {
        NSLog(@"Error: %@", error.description);
    }
    return availableGiga;
}