ios - Swift, check if array has value at index -

ios - Swift, check if array has value at index -

var cellheights: [cgfloat] = [cgfloat]() if allow height = self.cellheights[index] as? cgfloat { self.cellheights[index] = cell.frame.size.height } else { self.cellheights.append(cell.frame.size.height) }

i need check whether element @ specified index exists. above code not work, build error:

conditional downcast cgfloat cgfloat succeeds

i tried with:

if allow height = self.cellheights[index] {}

but failed:

bound value in conditional binding must of optional type

any ideas whats wrong?

cellheights array containing non-optional cgfloat. of elements cannot nil, such if index exists, element on index cgfloat.

what trying possible if create array of optionals:

var cellheights: [cgfloat?] = [cgfloat?]()

and in case optional binding should used follows:

if allow height = cellheights[index] { cellheights[index] = cell.frame.size.height } else { cellheights.append(cell.frame.size.height) }

i suggest read 1 time again optionals

ios swift nsarray