ios - View size is automatically being set to window size, when one of window's subview is removed -

i have 2 views 1 of them mainvideoview (grey color) , other subvideoview (red color). both of them subviews of uiapplication.shared.keywindow.

when try , minimise them (using func minimiseormaximiseviews, minimised (as shown in below image).

after which, remove subvideoview window. moment try , remove subvideoview (using func removesubvideoviewfromvideoview() called func minimiseormaximiseviews), mainvideoview enlarges full screen size, not sure why happening, want stay @ same size.

could please advise/ suggest how achieve ?

this how setting views

func configurevideoview(){   videoview.backgroundcolor    = uicolor.darkgray   videoview.tag                = 0    // identify view during animation    // adding tap gesture maximise view when small   let tapgesturerecognizer = uitapgesturerecognizer(target: self, action: #selector(handletap(gesturerecognizer:)))   videoview.addgesturerecognizer(tapgesturerecognizer)    // adding pan gesture recogniser make videoview movable inside parent view   videoview.addgesturerecognizer(uipangesturerecognizer(target: self, action: #selector(self.dragview)))     guard let window = uiapplication.shared.keywindow else{     return   }    window.addsubview(videoview)    videoview.translatesautoresizingmaskintoconstraints = false    let viewsdict = ["videoview" : videoview] [string : any]    // setting constraints    window.addconstraints(nslayoutconstraint.constraints(withvisualformat: "h:|[videoview]|", options: [], metrics: nil, views: viewsdict))    window.addconstraints(nslayoutconstraint.constraints(withvisualformat: "v:|[videoview]|", options: [], metrics: nil, views: viewsdict))     window.layoutifneeded() // lays out subviews   window.bringsubview(tofront: videoview) // bring subview front    print("videoview constraints in configurevideoview \(videoview.constraints)")  }  func configuresubvideoview(){      subvideoview.backgroundcolor    =   uicolor.red     subvideoview.tag                =   1    // identify view during animation     subvideoview.ishidden           = true       // adding pan gesture recogniser make subvideoview movable inside parentview     subvideoview.addgesturerecognizer(uipangesturerecognizer(target: self, action: #selector(self.dragview)))      // constraining subvideoview window ensure minimising , maximising animation works     constrainsubvideoviewtowindow()  }  func constrainsubvideoviewtowindow(){      //self.subvideoview.setneedslayout()     guard let window = uiapplication.shared.keywindow else{         print("window not exist")         return     }      guard !window.subviews.contains(subvideoview)else{  // not allow go through below code if window contains subvideoview         return     }      if self.videoview.subviews.contains(subvideoview){ // if videoview contains subvideoview remove subvideoview          subvideoview.removefromsuperview()      }      window.addsubview(subvideoview)         // default constraints ensure subvideoview initialised maxsubvideoviewwidth & maxsubvideoviewheight , positioned above buttons      let bottomoffset    =   buttondiameter + buttonstackviewbottompadding + padding      subvideoview.translatesautoresizingmaskintoconstraints = false      let widthconstraint = nslayoutconstraint(item: subvideoview, attribute: .width, relatedby: .equal, toitem: nil, attribute: nslayoutattribute.notanattribute, multiplier: 1.0, constant: maxsubvideoviewwidth)      let heightconstraint = nslayoutconstraint(item: subvideoview, attribute: .height, relatedby: .equal, toitem: nil, attribute: nslayoutattribute.notanattribute, multiplier: 1.0, constant: maxsubvideoviewheight)      let rightconstraint = nslayoutconstraint(item: subvideoview, attribute: .trailing, relatedby: .equal, toitem: window, attribute: .trailing, multiplier: 1.0, constant: -padding)      let bottomconstraint = nslayoutconstraint(item: subvideoview, attribute: .bottom, relatedby: .equal, toitem: window, attribute: .bottom, multiplier: 1.0, constant: -bottomoffset)      var constraintsarray = [nslayoutconstraint]()     constraintsarray.append(widthconstraint)     constraintsarray.append(heightconstraint)     constraintsarray.append(rightconstraint)     constraintsarray.append(bottomconstraint)      window.addconstraints(constraintsarray)      window.layoutifneeded() // lays out subviews     subvideoview.setviewcornerradius()     window.bringsubview(tofront: subvideoview) // bring subview front  } 

this how animating views , removing subvideoview

func minimiseormaximiseviews(animationtype: string){      let window = uiapplication.shared.keywindow      let buttonstackviewheight = buttonsstackview.frame.height      if animationtype == "maximiseview" {         constrainsubvideoviewtowindow()      }       uiview.animate(withduration: 0.3, delay: 0, options: [],          animations: { [unowned self] in  // "[unowned self] in" added avoid strong reference cycles,             switch animationtype {              case "minimiseview" :                  self.hidecontrols()                  // minimising self i.e videoview                 self.videoview.frame = cgrect(x:      self.mainscreenwidth - self.videoviewwidth - self.padding,                                               y:      self.mainscreenheight - self.videoviewheight - self.padding,                                               width:  self.videoviewwidth,                                               height: self.videoviewheight)                   // minimising subvideoview                 self.subvideoview.frame =   cgrect(x:       self.mainscreenwidth - self.minsubvideoviewwidth - self.padding * 2,                                                    y:       self.mainscreenheight - self.minsubvideoviewheight - self.padding * 2,                                                    width:   self.minsubvideoviewwidth,                                                    height:  self.minsubvideoviewheight)                 window?.layoutifneeded()                   self.videoview.setviewcornerradius()                 self.subvideoview.setviewcornerradius()                  print("self.subvideoview.frame after setting: \(self.subvideoview.frame)")                default:                 break             }     }) { [unowned self] (finished: bool) in   // called when animation completes, , finished value true         if animationtype == "minimiseview" {              //  **** removing subvideoview videoview ****             self.removesubvideoviewfromvideoview()           }     }   }  func removesubvideoviewfromvideoview(){      //self.subvideoview.setneedslayout()      guard let window = uiapplication.shared.keywindow else{         return     }      guard !self.videoview.subviews.contains(subvideoview)else{  // not allow go through below code if videoview contains subvideoview         return     }      if window.subviews.contains(subvideoview) {     // removing subvideoview window         subvideoview.removefromsuperview() // *** cause of issue ***      }      guard !window.subviews.contains(subvideoview) else{         return     }      videoview.addsubview(subvideoview) } 

the videoview , subvideoview layout auto layout. in auto layout if want change frame, have update constraints.

calling removefromsuperview removes constraints refer view removing, or refer view in subtree of view removing. means auto layout system rearrange views.