Generate Segwit P2SH-P2WPKH address, create tx spending from it.

p2sh_p2wpkh.rb

require 'bitcoin'

include Bitcoin
include Bitcoin::Builder
include Bitcoin::Protocol
include Bitcoin::Util
include Bitcoin::Secp256k1

# Compute P2SH-P2WPKH address:

compressed_public_key = "02530c548d402670b13ad8887ff99c294e67fc18097d236d57880c69261b42def7"
redeem_script = Script.from_string("0 #{hash160(compressed_public_key)}").to_payload
p2sh__p2wpkh_address = hash160_to_p2sh_address(hash160(redeem_script.bth))

# Build Segwit transaction spending from P2SH-P2WPKH address:

utxo_txid="4ec4f658d86549544ac0b7b4f62ff4225f458c97243c7abf17e67584e27d0d08"
utxo_index = 0
amount = 100000
fee = 15000
@destination_address = "1Bwyn5f5EvUPazh3H2rns6ENjTUYnK9ben"

spend_tx = build_tx do |t|
  t.lock_time 0
  t.input do |i|
    i.prev_out utxo_txid, utxo_index, redeem_script, amount
    i.sequence "ffffffff".htb
  end
  t.output do |o|
    o.value amount-fee
    o.script {|s| s.recipient @destination_address }
  end
end

tx = Tx.new(spend_tx.to_payload) # unsigned tx
tx.in[0].script_sig = Script.new(Script.pack_pushdata(redeem_script)).to_payload
sig_hash = tx.signature_hash_for_witness_input(0, redeem_script, amount)
private_key_hex = "25940ad..f7b2d9"
sig = Secp256k1.sign(sig_hash, private_key_hex.htb)
tx.in[0].script_witness.stack << sig + [Tx::SIGHASH_TYPE[:all]].pack("C")
tx.in[0].script_witness.stack << compressed_public_key.htb
tx.to_witness_payload.bth # signed tx