Optional chaining and Array in swift -

let's take these 2 simple classes show problem:

class object{       var name:string?     // keep simple... , useless }  class testclass {     var objects:anyobject[]?       func initializeobjects (){         objects?.insert(object(), atindex:0) // error         objects?.insert(object(), atindex:1) // error         objects?.insert(object(), atindex:2) // error     } } 

with implementation 3 errors could not find member 'insert' try add object objects array.

now, if remove optional objects definition , optional chain in initializeobjects works no problem (here working code)

class object{     var name:string? }  class testclass {     var objects:anyobject[] = anyobject[]() // remove optional , initialize empty array      func initializeobjects (){         objects.insert(object(), atindex:0) // remove opt chaining          objects.insert(object(), atindex:1) // remove opt chaining         objects.insert(object(), atindex:2) // remove opt chaining     } } 

i can't understand wrong in first implementation. thought checks objects? if objects not nil , @ point adds element using insert:atindex:. i'm wrong -.-

arrays in swift structs , structs value types.
optionals in swift enums (optional<t> or implicitlyunwrappedoptional<t>).

when unwrapping optional (implicitly or explicitly) of value type, constant copy of struct. , can't call mutating methods on constant struct.

executing objects?.insert(object(), atindex:0) means this:

if let tmp = objects {     tmp.insert(object(), atindex:0) } 

as workaround, need assign unwrapped value variable , assign variable optional property. that's how value types work.

this reproducible struct, not arrays:

struct s {     var value: int = 0 }  var vars: s = s() vars.value = 10 //can called  let consts: s = s() consts.value = 10 //cannot called - constant!  var optionals: s? = s() optionals?.value = 10 //cannot called, unwrapping makes constant copy!  //workaround if optionals {     var tmps = optionals!     tmps.value = 10     optionals = tmps } 

some relevant discussion here: https://devforums.apple.com/thread/233111?tstart=60