It is a bit late, but maybe it helps you or others....
You can change the selection through the UITextInput-Protocol by setting the selectedTextRange .
let beginning: UITextPosition = textView.beginningOfDocument
let start: UITextPosition = textView.positionFromPosition(beginning, offset: textView.selectedRange.location)
let end: UITextPosition = textView.positionFromPosition(start!, offset: textView.selectedRange.length)
textView.selectedRange = NSMakeRange(0, 0)
textView.selectedTextRange = textView.textRangeFromPosition(start!, toPosition: end!)
P.S. My code is written in Swift, but I think it is no problem to convert that to objective c, or?