ios - Auto Layout using layout anchors programmatically not working -


i trying add stack view containing uilabel @ top , uicollectionview underneath. trying constrain stack view takes full view, anchoring sides. when run app uilabel appears , slice of collection view appears. collection view says width , height both zero. appreciated, thank you.

var collectionview: uicollectionview! var titlelabel: uilabel!  override func viewdidload() {     super.viewdidload()     // additional setup after loading view, typically nib.     self.view.translatesautoresizingmaskintoconstraints = false     let margins = self.view.layoutmarginsguide      let layout: uicollectionviewflowlayout = uicollectionviewflowlayout()     layout.sectioninset = uiedgeinsets(top: 20, left: 10, bottom: 10, right: 10)      collectionview = uicollectionview(frame: self.view.frame, collectionviewlayout: layout)     layout.itemsize = cgsize(width: self.collectionview.frame.width / 4, height: self.collectionview.frame.width / 4)     layout.minimuminteritemspacing = self.collectionview.frame.width / 15     layout.minimumlinespacing = self.collectionview.frame.width / 5      collectionview.backgroundcolor = uicolor.black     collectionview.datasource = self     collectionview.delegate = self     collectionview.register(uicollectionviewcell.self, forcellwithreuseidentifier: "cell")      titlelabel = uilabel()     titlelabel.translatesautoresizingmaskintoconstraints = false      titlelabel.textalignment = .center     titlelabel.numberoflines = 1     titlelabel.font = uifont.systemfont(ofsize: 22)     titlelabel.backgroundcolor = uicolor.lightgray     titlelabel.text = "challenges"     titlelabel.textcolor = uicolor.red      let stackview = uistackview(arrangedsubviews: [titlelabel, collectionview])     stackview.backgroundcolor = uicolor.white     stackview.axis = .vertical     stackview.distribution = .fillequally     stackview.alignment = .fill     stackview.spacing = 5     self.view.addsubview(stackview)     stackview.translatesautoresizingmaskintoconstraints = false      //stackview.centerxanchor.constraint(equalto: self.view.centerxanchor).isactive = true     //stackview.centeryanchor.constraint(equalto: self.view.centeryanchor).isactive = true     stackview.topanchor.constraint(equalto: self.view.topanchor).isactive = true     stackview.leadinganchor.constraint(equalto: self.view.leadinganchor).isactive = true     stackview.trailinganchor.constraint(equalto: self.view.trailinganchor).isactive = true     stackview.bottomanchor.constraint(equalto: self.view.bottomanchor).isactive = true     stackview.heightanchor.constraint(equalto: self.view.heightanchor, multiplier: 1.0).isactive = true  }

update:

i took code , ran in new single view application , worked expected. because of think worth mention trying incorporate sprite kit game , present view controller doing this:

let root = self.view?.window?.rootviewcontroller var viewc = selectioncollectionviewcontroller() root?.present(viewc, animated: false, completion: nil)

are there special steps need take because done sprite kit?

i believe below screen shot expected output.

enter image description here

you might not need uistackview , can directly add self.view.

once added self.view, can set constraints. can print item size in viewdidlayoutsubviews

class viewcontroller: uiviewcontroller {      var collectionview: uicollectionview!     var titlelabel: uilabel!     let collectioncellidentifier:string = "collectioncellid"      override func viewdidload() {         super.viewdidload()         // additional setup after loading view, typically nib.          let layout: uicollectionviewflowlayout = uicollectionviewflowlayout()         layout.sectioninset = uiedgeinsets(top: 20, left: 10, bottom: 10, right: 10)          collectionview = uicollectionview(frame: cgrect.zero, collectionviewlayout: layout)         collectionview.delegate = self         collectionview.datasource = self         collectionview.register(uicollectionviewcell.classforcoder(), forcellwithreuseidentifier: collectioncellidentifier)          collectionview.backgroundcolor = uicolor.black         collectionview.datasource = self         collectionview.delegate = self         collectionview.register(uicollectionviewcell.self, forcellwithreuseidentifier: "cell")          titlelabel = uilabel()           titlelabel.textalignment = .center         titlelabel.numberoflines = 1         titlelabel.font = uifont.systemfont(ofsize: 22)         titlelabel.backgroundcolor = uicolor.lightgray         titlelabel.text = "challenges"         titlelabel.textcolor = uicolor.red         titlelabel.translatesautoresizingmaskintoconstraints =  false         collectionview.translatesautoresizingmaskintoconstraints = false         self.view.addsubview(titlelabel)         self.view.addsubview(collectionview)          setupconstraints()     }       func setupconstraints(){         self.view.addconstraint(nslayoutconstraint(item: self.titlelabel, attribute: .height, relatedby: .equal, toitem: nil, attribute: .notanattribute, multiplier:0, constant:50.0 ))         titlelabel.topanchor.constraint(equalto: self.view.topanchor).isactive = true         titlelabel.leadinganchor.constraint(equalto: self.view.leadinganchor).isactive = true         titlelabel.widthanchor.constraint(equalto: self.view.widthanchor).isactive = true           collectionview.topanchor.constraint(equalto: titlelabel.bottomanchor).isactive = true         collectionview.leadinganchor.constraint(equalto: self.view.leadinganchor).isactive = true         collectionview.trailinganchor.constraint(equalto: self.view.trailinganchor).isactive = true         collectionview.bottomanchor.constraint(equalto: self.view.bottomanchor).isactive = true     }      override func viewdidlayoutsubviews() {         super.viewdidlayoutsubviews()         let flowlayout = (collectionview.collectionviewlayout as! uicollectionviewflowlayout)         flowlayout.itemsize = cgsize(width: collectionview.frame.width / 4.0 , height: collectionview.frame.width / 4.0)         flowlayout.minimuminteritemspacing = self.collectionview.frame.width / 15.0         flowlayout.minimumlinespacing = self.collectionview.frame.width / 5.0     }   }  extension viewcontroller:uicollectionviewdatasource,uicollectionviewdelegate {       func numberofsections(in collectionview: uicollectionview) -> int {         return 1     }       func collectionview(_ collectionview: uicollectionview, numberofitemsinsection section: int) -> int {         return 10     }      func collectionview(_ collectionview: uicollectionview, cellforitemat indexpath: indexpath) -> uicollectionviewcell {         let cell = collectionview.dequeuereusablecell(withreuseidentifier: collectioncellidentifier, for: indexpath)         cell.backgroundcolor = uicolor.gray         return cell     }  }

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