King's blood reading was 55mg, under the adult limit of 80mg but over the youth limit of zero.
Defence lawyer Philip Morgan said King had misjudged the road and asked the judge to consider a lesser sentence than the maximum three years' imprisonment.
Mr Morgan said a crash investigation unit report calculated the maximum speed for the corner was 89 km/h.
"Police calculated the defendant was going faster than that, something like 96 to 120 kilometres an hour."
It may have been foggy and it was thought the black and white chevron boards warning drivers to slow down on the corner were not visible, Mr Morgan said.
"In the CIU report, a visit to this at night found no reflectivity at all, offering no warning to drivers." But this was not the cause of the crash, Mr Morgan said.
"This young man had been drinking and shouldn't have been driving at all."
He said King's early guilty plea, his age at the time of the offence - 18, his good character, the fact that had killed a close friend and his mental health should be taken into account.
Mr Swinbank's family also did not want to see King go to jail, Mr Morgan said.
Judge Barbara Morris said 12 months' imprisonment was appropriate but reduced the sentence due to a number of factors.
"You and your friend Mr Swinbank had just finished your term at Taratahi, the world was at your feet."
King had no previous offences, had undertaken alcohol counselling, was young, had pleaded guilty and had been affected mentally by the death of his friend, she said.
"It was an area that was not known to you, you took a corner too fast, it seems the reflection was not as good as what it could have been.
"You careened into a paddock, you rolled into a power pole shattering it and the life of your friend was shattered with it.
"You lay trapped in the car for a number of hours knowing he had died at your hands."
Judge Morris said she had read the psychologist's report and about how King had attempted to take his own life.
"You have been asking yourself regularly why him and not you."
She said the probation officer report stated there was an overwhelming sense of remorse.
"There can be little doubt that it is genuine," said Judge Morris.
Mr Swinbank's mother was at the sentencing, crying in the public gallery.
She declined to comment on the outcome, outside of court.
