After making seven pars in a row, followed by a birdie on the 17th, the Napier golfer had taken sole possession of the lead and stood on the final hole four shots in front.
Packed full of adrenaline, Swanwick blasted his third shot to the par 5 final hole over the green and out of bounds, leaving the door slightly ajar for Liu. However, he kept his composure, hitting his fourth shot short of the green, where he was able to make up and down to save his bogey and win by three.
He said it felt great to come from behind and win a national title.
"I'm really stoked. It was a tough fight out there; I really had to work for it, but it was awesome.
"I just wanted to hit 18 greens; that's all I was working on. If I'm hitting lots of greens, it minimises the chance of making bogeys, so that was a big part of the game plan today."
He said his heart rate increased after hitting his second shot on the last hole out of bounds, but was happy with a final round of 69.
"That was tough. My heart was in my mouth for a second there. Thankfully, I hit my provisional short, so I could chip it up to the hole and hole the putt. I'm smiling."
In the Under-19 girls' division, Amy Im led from start till finish, shooting 70, 74, and 74 to finish one-under and win by three over Espirito Santo Trophy team member and fellow North Harbour player, Eunseo Choi.
Like Im, Clearwater's Cooper Moore was dominant all week, but needed to hold his nerve up the 18th to capture the Under-16 boys' title.
In the Under-16 girls, Yoonae Jeong came from seven shots behind to win her first national title.
