// Check that you have a minimum amount of disk space free on an iPhoneOS device
- (BOOL)hasDiskSpaceAvailable {
    NSUInteger minimumDiskSpace = 400 * 1024 * 1024; // 400MB limit

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);

    struct statfs tStats;

    statfs([[paths lastObject] cString], &tStats);

    NSUInteger availableDisk = tStats.f_bavail * tStats.f_bsize;

    NSLog(@"Available disk is %d", availableDisk);

    if (availableDisk < minimumDiskSpace) { // availableDisk is less than 400MB
        return NO;
    } else {
        return YES;
    }
}