ios - Center UIView in center of MainScreen Despite Location of Superview -

i have uiview can dragged around. in uiview have subview want centered on device screen both height , width. ever try centers superview. how can make subview @ center of uidevice mainscreen despite uiview is.

i have (stripped down because 50000 lines long):

    popartwork = [uiimageview new];     popartwork.frame = cgrectmake(367, 367, widgetwidth, widgetwidth/5.3);      popartwork.layer.cornerradius = 10;     popartwork.layer.maskstobounds = yes;     popartwork.alpha = 0;     [popartwork setuserinteractionenabled:yes];     [add addsubview:popartwork]; 

add superview. program little unusual in way music widget user's home screen (jailbreak tweak) can move ever. want view popartwork in center of screen despite wherever add might be.

i don't know if it's looking for, how center subview when superview re-positioned:

- (void)viewdidload {     [super viewdidload];      uipangesturerecognizer *pan = [[uipangesturerecognizer alloc] initwithtarget:self action:@selector(paned:)];     [_add addgesturerecognizer:pan];  }   -(void)paned:(uipangesturerecognizer *)pan{      cgpoint translatedpoint = [(uipangesturerecognizer*)pan translationinview:self.view];      if ([(uipangesturerecognizer*)pan state] == uigesturerecognizerstatebegan) {         firstx = [[pan view] center].x;         firsty = [[pan view] center].y;     }      translatedpoint = cgpointmake(firstx+translatedpoint.x, firsty+translatedpoint.y);      [[pan view] setcenter:translatedpoint];       cgrect newsubviewframe = _subview.frame;     newsubviewframe.origin.x = [uiscreen mainscreen].bounds.size.width/2.0 - newsubviewframe.size.width/2.0 - _add.frame.origin.x;     newsubviewframe.origin.y = [uiscreen mainscreen].bounds.size.height/2.0 - newsubviewframe.size.height/2.0 - _add.frame.origin.y;     _subview.frame = newsubviewframe;  }