Swans ride Barn storm
the bar and Swans keeper Freddie Woodman brilliantly denied Cauley Woodrow late on.
But McGeehan should have given his side a two-goal cushion before all that late action.
Six minutes after the restart he failed to find the target from point-blank range, after being set up by Conor Chaplin, to complete a miserable afternoon.
The struggling hosts could have been two goals up inside the opening quarter of an hour.
Within two minutes, Woodman rescued his side with an instinctive save at his near post after Woodrow flicked on a long throw-in from Dimitri Cavare.
McGeehan was then guilty of his first clanger 12 minutes later when he blazed over with the goal at his mercy.
Barnsley threatened to turn the formbook upside down, but Swansea gradually found a foothold and Brad Collins in the Tykes’ goal was powerless to prevent Ayew stabbing home.
Barnsley refused to lie down, however, and skipper Mowatt coolly converted Chaplin’s cross.
Swansea manager Steve Cooper was frustrated his team failed to win.
“Having got through the opening hour and then taken control of the game and gone one up, it was quite frustrating to then concede the way we did,” he said.
SWANSEA 5 ........ Shots on Target .........8 12 ....... Shots off Target .........3 2 ................Corners .................5 8 .................. Fouls ....................5 3 ............... Offsides ................. 3 67.1 ..Passing Success % . 74.6 304 ...... Total Passes ........468 39.7 ..... Possession % .....60.3 54.4 .Territorial Adv % .. 45.6