Joshua, make sure to use the developers documentation to determine whether or not it’s a delegate method. If it were a delegate method, it would be mentioned in the docs for NSTableViewDelegate.
What you’re looking for is very straight forward.
Objective-C
NSIndexSet *indexSet = [NSIndexSet indexSetWithIndex:1];
[tableview selectRowIndexes:indexSet byExtendingSelection:NO];
Swift 2
let indexSet = NSIndexSet(index: 1)
tableView.selectRowIndexes(indexSet, byExtendingSelection: false)
Again. Make sure to look up the method selectRowIndexes:byExtendingSelection in the docs to see what parameters it needs. It says an NSIndexSet is needed. Then look up NSIndexSet and you’ll discover how to use that.