objective c - Setting NSWindow position in current screen -

i newbie in objective-c.i have created main window want display in right bottom of current screen. tried following code

- (void)windowdidload {     nspoint pos;      pos.x = [[nsscreen mainscreen] visibleframe].origin.x + [[nsscreen mainscreen] visibleframe].size.width - [mywindow frame].size.width ;      pos.y = [[nsscreen mainscreen] visibleframe].origin.y + [[nsscreen mainscreen] visibleframe].size.height - [mywindow frame].size.height;      [mywindow setframetopleftpoint:pos];  } 

what wrong in it? how resolve it?

use

nspoint pos;  pos.x = [[nsscreen mainscreen] frame].size.width - [mywindow frame].size.width ;  pos.y = 0.0f;  [self.window setframe:cgrectmake(pos.x, pos.y, [mywindow frame].size.width , [mywindow frame].size.height) display:yes]; 

because [[nsscreen mainscreen] frame].origin.x 0. , in case of mac screen starts bottom.