swift - how can the UILabel become a CALayer and cause a crash? -

i've got custom uiview of several instances created inside loop:

let models = cdmymodel.mr_findallsortedby("position", ascending: true) as! [cdmymodel]  view in myviews {     view.removefromsuperview() }  self.myviews.removeall(keepcapacity: true)  model in models {     let myview = myfaqview(width: cgrectgetwidth(self.view.frame))     myview.titlelabel.text = model.title     myview.content.text = model.content     myview.titlelabel.sizetofit()     self.scrollview.addsubview(myview)     self.myviews.append(myview) } 

i see crashes in crashlytics in line myview.content.text = model.content:

according crash assume has memory, don't know how myview have been released @ point.

all happens in viewwillappear:. removing before has this? assume happens on main thread, shouldn't problem - i'm stuck here.

the crash happens on ios 9.

edit

myfaqview init method:

init(width:cgfloat) {     self.width = width      super.init(frame: cgrectzero)      self.addsubview(self.titlelabel)     self.addsubview(self.toggleimageview)     self.addsubview(self.separatorview)     self.content.clipstobounds = true     self.addsubview(self.content)      self.translatesautoresizingmaskintoconstraints = false     self.clipstobounds = true } 

edit

let content:uilabel = {     let l = uilabel()     l.numberoflines = 0     if let font = uifont(name: "opensans", size: 14) {         l.font = font     }     return l }() 

these problems tricky track down.

basically, happening memory corruption. address 0x14f822a0 occupied uilabel content has been used else, in case calayer. can verify if crash happens locally entering po 0x14f822a0 in lldb , sure enough output address of type calayer.

with these errors, although crash line can provide clue, not cause of error. has happened elsewhere.

although swift memory managed, there still pitfalls unwary. have seen 2 principal causes of memory corruption. first retain cycles caused self referencing closures. second - more pertinent problem - views related storyboards , xibs.

if follow through logically, can consider calayer occupies address space taken uilabel content. runtime attempts send message object thinks occupies address, , caught swift runtime assert triggers exc_bad_instruction crash.

now, other object have taken residence @ address, original inhabitant uilabel content must have been released. why runtime release content? because no longer required, i.e. not subview or property of view still required.

i bet if change content subclass uilabel , add deinit method breakpoint, surprised see being unexpectedly deinitialised on. test create type follows:

class debuglabel: uilabel {    func deinit    {      nslog("breakpoint on line here!")    } } 

then change content's type debuglabel above.

so why happening? money on having 1 of view properties has been created programmatically being either weak or unowned. perhaps had these set using iboutlet removed forgot remove weak designator?

check through each , every 1 , sure find cause of problem above. nothing created programatically either using initialiser or uinib should designated weak or unowned.