swift - HealthKit (Unexpectedly found nil when unwrapping an optional) -

when try read data in healthkit error telling me application crashed because of

fatal error: unexpectedly found nil while unwrapping optional value

i understand trying unwrap optional nil, when try use optionals error telling me force unwrap it.

here of code using:

import foundation import healthkit import uikit  class healthmanager { let healthkitstore = hkhealthstore()  func authorizehealthkit(completion: ((success: bool, error: nserror) -> void)!) {     // set data read healthkit store     let healthkittypestoread: set<hkobjecttype> = [(hkobjecttype.quantitytypeforidentifier(hkquantitytypeidentifieractiveenergyburned))!, hkobjecttype.quantitytypeforidentifier(hkquantitytypeidentifierflightsclimbed)!, hkobjecttype.quantitytypeforidentifier(hkquantitytypeidentifiernikefuel)!, hkobjecttype.quantitytypeforidentifier(hkquantitytypeidentifierstepcount)!, hkobjecttype.quantitytypeforidentifier(hkquantitytypeidentifierdistancewalkingrunning)!]      // check if healthkit available     if !hkhealthstore.ishealthdataavailable() {         let error = nserror(domain: "com.mycompany.appname", code: 2, userinfo: [nslocalizeddescriptionkey: "healthkit not available on device"])         if completion != nil {             completion?(success: false, error: error)         }         return;     }      // request healthkit access     self.healthkitstore.requestauthorizationtosharetypes(nil, readtypes: healthkittypestoread) {         (success, error) -> void in         if completion != nil {             completion?(success: true, error: error!)         }     } } } 

also, if try remove bang operator(!) error saying that:

value of optional type 'hkquantitytype?' not unwrapped; did mean use '!'?

since quantitytypeforidentifier returns hkquantitytype?, force unwrapping can result in unwrapping nil value, know. have check nil, example in form:

if let objecttype = hkobjecttype.quantitytypeforidentifier(hkquantitytypeidentifierflightsclimbed) {     // add objecttype set }