ios - Core Motion Swift Closure issue -

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i'm trying convert old game application built in obj-c new swift code. i'm having issues understanding swift closures , how use them example in the"startaccelerometerupdatestoqueue" method.

i have initialized motion manager in way 

motionmanager!.accelerometerupdateinterval = (1/40)

then in viewdidload of view controller

var queue:nsoperationqueue motionmanager?.startaccelerometerupdatestoqueue(queue, withhandler: {(accelerometerdata :     cmaccelerometerdata, error : nserror) in   })

the "startaccelerometerupdatestoqueue" giving me error , i'm pretty sure didn't understand correct closure syntax.

any ideas?

actually, got signature wrong – arguments closure need optionals (since passed objective-c, nil). because of that, arguments provide don't match existing method signature, , because of error.

take @ ios 8 api docs, provide swift signatures:

func startaccelerometerupdatestoqueue(_ queue: nsoperationqueue!,                           withhandler handler: cmaccelerometerhandler!)

and cmaccelerometerhandler defined as

typealias cmaccelerometerhandler = (cmaccelerometerdata!, nserror!) -> void

thus, call should be:

motionmanager?.startaccelerometerupdatestoqueue(queue, withhandler: {(accelerometerdata :     cmaccelerometerdata!, error : nserror!) in   })

and function/method takes closure it's last argument, can leave out of argument list , write after call (trailing closure syntax – example leaves out types, can inferred, optional):

motionmanager?.startaccelerometerupdatestoqueue(queue) { accelerometerdata, error in  }

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