ios - Filter array of custom objects in Swift -

i'm trying filter array of custom objects in swift subset of data has properties want isolate. code follows.

func generatesubset( datapool : [customobject]) -> [customobject]? {              let subsetdata = datapool.filter{(includeelement:customobject)-> bool in                 return contains(includeelement.position, "teacher")             }          return subsetdata     } 

my custom object follows:

   class customobject :  {         var position : string?          init(){           position = ""         }     } 

however error xcode throws me when trying compile code is:

cannot invoke 'filter' argument list of type [customobject] -> bool 

i'm using swift 1.2 , can't seem figure out i'm doing wrong. appreciated.

in swift 1.2, filter global function, can't datapool.filter(...). (in swift 2, work.)

furthermore, contains can't used strings that. recommend using rangeofstring: method nsstring:

let teachers = filter(datapool) { // in swift 2 "datapool.filter {"     return $0.position!.rangeofstring("teacher") != nil }