Reading in receipt Prt 1 in Swift

Receipt_validation_prt1.swift

//Get the Path to the receipt
let receiptUrl = Bundle.main.appStoreReceiptURL //Swift2 : NSBundle.mainBundle().appStoreReceiptURL

//Check if it's actually there
if FileManager.default.fileExists(atPath: receiptUrl!.path) //Swift 2: NSFileManager.defaultManager().fileExistsAtPath(receiptUrl!.path!)
{
    //Load in the receipt
    //Swift 2: let receipt: NSData = try! NSData(contentsOfURL:receiptUrl!, options: [])
    //Swift 3
    let receipt: Data = try! Data(contentsOf: receiptUrl!, options: [])
    let receiptBio = BIO_new(BIO_s_mem())
    
    //Swift 2: BIO_write(receiptBio, receipt.bytes, Int32(receipt.length))
    //Swift 3
    BIO_write(receiptBio, (receipt as NSData).bytes, Int32(receipt.count))
    let receiptPKCS7 = d2i_PKCS7_bio(receiptBio, nil)
    //Verify receiptPKCS7 is not nil
    
    //Read in Apple's Root CA
    //Swift 2
    //let appleRoot = NSBundle.mainBundle().URLForResource("AppleIncRootCertificate", withExtension: "cer")
    //Swift 3
    let appleRoot = Bundle.main.url(forResource: "AppleIncRootCertificate", withExtension: "cer")
    let caData = try? Data(contentsOf: appleRoot!) //Swift 2: let caData = Data(contentsOfURL: appleRoot!)
    let caBIO = BIO_new(BIO_s_mem())
    BIO_write(caBIO, (caData! as NSData).bytes, Int32(caData!.count)) //Swift 2: BIO_write(caBIO, caData!.bytes, Int32(caData!.length))
    let caRootX509 = d2i_X509_bio(caBIO, nil)
                
    //Verify the receipt was signed by Apple
    let caStore = X509_STORE_new()
    X509_STORE_add_cert(caStore, caRootX509)
    OpenSSL_add_all_digests()
    let verifyResult = PKCS7_verify(receiptPKCS7, nil, caStore, nil, nil, 0)
                
    if verifyResult != 1 {
        print("Validation Fails!")
        return
    }
}