ios - Making HTTP request with AlamoFire causes EXC_BAD_ACCESS -

i'm working on simple project learn swift , i'm running problem think has deeper implications / learning opportunities (trying on bright side).

the high-level problem when post json-encoded parameters using alamofire, exc_bad_access error appears in separate line of code set 1 of parameters (specifically corelocation manager's "didupdatelocations") ... here's code:

in viewcontroller, create mutable dictionary:

var parameters = [string:anyobject]() 

and, didupdatelocations event, assign updated latitude / longitude values respective keys in mutable dictionary.

class viewcontroller: uiviewcontroller, cllocationmanagerdelegate {     let appdelegate = uiapplication.sharedapplication().delegate appdelegate     ...     func locationmanager(locmanager: cllocationmanager!, didupdatelocations locations: [anyobject]!) {         appdelegate.parameters["longitude"] = locmanager.location.coordinate.longitude         appdelegate.parameters["latitude"] = locmanager.location.coordinate.latitude     } 

finally, have periodic function (using nstimer.scheduledtimerwithtimeinterval) posts server.

func updatepost() {     println("posting update")      alamofire.request(.post, "http://server.co/endpoint",             parameters: appdelegate.parameters, encoding: .json) } 

if comment out alamofire post, fine. with post, exc_bad_access error @ first line of didupdatelocations (where longitude key set)

i suspect it's how parameters converted encoding routine of alamofire, have no idea why appear in didupdatelocations function , not in alamofire call ...

can provide insights? thank you

what's happening have multiple threads trying access dictionary @ same time. when modify parameters in didupdatelocations, moves in memory while it's being read inside alamofire, causing exc_bad_access exception.

to solve stop updating parameters dictionary within didupdatelocations - add latestlocation property view controller , update instead. then, inside updatepost, create dictionary of parameters , pass alamofire.request.