ios - Add border to bottom of .xib (objective-c) -

i trying add border bottom of .xib view. have following code places red border on 4 sides. want border on 1 side, bottom... how set border bottom?

current code class controls .xib:

- (void)awakefromnib {      self.contentview.layer.borderwidth  = 5.0f;     self.contentview.layer.maskstobounds = yes;     self.contentview.layer.bordercolor  = [uicolor redcolor].cgcolor; } 

this get:

  calayer *bottomborder = [calayer layer];   bottomborder.bordercolor = [uicolor redcolor].cgcolor;   bottomborder.borderwidth = 1;   bottomborder.frame       = cgrectmake(0, self.contentview.frame.size.height - bottomborder.borderwidth, self.contentview.frame.size.width, bottomborder.borderwidth);   [self.contentview.layer addsublayer:bottomborder];