ios - Swift 3: prepare(for:sender:) -

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this question has answer here:

i have simple entity:

extension team {  @nonobjc public class func fetchrequest() -> nsfetchrequest<team> {     return nsfetchrequest<team>(entityname: "team") }  @nsmanaged public var name: string? @nsmanaged public var phone: string? @nsmanaged public var department: string? @nsmanaged public var position: string?  }

picture easy understanding:

enter image description here

i load current entity core data app successfully. furthermore, have uitableviewcontroller property members (it's storage of fetch result team entity).

var members: [team] = []

after app launching (viewdidload(_:)) members.count equal 7 , right. also, these elements of members using uitableview in uitableviewcontroller:

enter image description here

my task open detailed view controller retrieve data tapped cell. delegation use classic prepare(for:sender:) method in uitableviewcontroller (who segue.source in current case):

// mark: - navigation  extension teamlistviewcontroller {  override func prepare(for segue: uistoryboardsegue, sender: any?) {     guard segue.identifier == segueidentifier,         let memberdetailsviewcontroller = segue.destination as? memberdetailsviewcontroller else {         fatalerror("wrong destination!")     }      guard let selectedindex = tableview.indexpathforselectedrow?.row else {         fatalerror("out of range")     }      guard let name       = members[selectedindex].name,           let phone      = members[selectedindex].phone,           let department = members[selectedindex].department,           let position   = members[selectedindex].position else {          fatalerror("no correct data")     }      memberdetailsviewcontroller.membernamelabel.text!        = name     memberdetailsviewcontroller.memberphonenumberlabel.text! = phone     memberdetailsviewcontroller.memberdepartmentlabel.text!  = department     memberdetailsviewcontroller.memberpositionlabel.text!    = position  }  }

so, app launches, tap cell whichever want open more details and.. app crashes!

fatal error: unexpectedly found nil while unwrapping optional value

enter image description here

however, variables (name, phone, department, position) ok. values!

enter image description here

oh, yes. try retrieve data uilabels in memberdetailsviewcontroller below:

// mark: - iboutlets @iboutlet weak var membernamelabel:        uilabel! @iboutlet weak var memberphonenumberlabel: uilabel! @iboutlet weak var memberdepartmentlabel:  uilabel! @iboutlet weak var memberpositionlabel:    uilabel!

what can problem here?

because of set data in prepare(for segue: uistoryboardsegue, sender: any?) method in teamlistviewcontroller memberdetailsviewcontroller not loaded thats way got nil.

my suggestion is: add object var members: team? in memberdetailsviewcontroller , pass teamlistviewcontroller error not appear.





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