Swift - '[Subject] does not have a member named 'name' '

Question

I have two lists of subjects in my app. The user can choose several subjects from the second list to add these to the first one. I now have problems with the adding process.

The cells from the second list are described by this:

override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCellWithIdentifier("AddSubjectCell", forIndexPath: indexPath) as! AddSubjectCell

    let subject = Subjects[indexPath.row] as Subject
    let Semester = "\(subject.semester)"

    cell.nameLabel.text = subject.name

    cell.semesterLabel.text = "Semester"

    cell.semesterNumberLabel.text = Semester

    return cell

}

and take their data from this array:

var addSubjectsData = [ Subject(name: "A", semester: 1), Subject(name: "B", semester: 2), Subject(name: "C", semester: 3), Subject(name: "D", semester: 5), Subject(name: "E", semester: 6) ]

If the user checkmarked the cell, this part of a function is activated:

 if cell.accessoryType == UITableViewCellAccessoryType.Checkmark {
        selectedCellsData.append(Subject(name: selectedCellsData.last!.name, semester: selectedCellsData.last!.semester))

Hereby,

    selectedCellsData.name = cell.nameLabel.text!
    selectedCellsData.semester = cell.semesterNumberLabel.text!.toInt()!

The array that I am trying to append is defined as var selectedCellsData = [ Subject(name: "Initial Subject", semester: 0)].

On the screen of the second list is a done button. If it is pressed, this action is being activated:

 @IBAction func saveSubjectDetail(segue:UIStoryboardSegue) {

    subjectsData.append(Subject(name: selectedCellsData.last!.name, semester: selectedCellsData.last!.semester))

The selected cells' data should then be added to the array var subjectsData = [ Subject(name: "Investments", semester: 1), Subject(name: "Statistics", semester: 1), Subject(name: "Studium Universale", semester: 2) ].

Trying to run the simulator, I receive the error "[Subject] does not have a member named 'name'". Though, as it can be seen in my array, there is a member called 'name'.

Also, when I declared the class 'Subject', I also added 'name':

class Subject: NSObject {
    var name: String
    var semester: Int

    init(name: String, semester: Int) {
        self.name = name
        self.semester = semester
        super.init()
    }
}

I would appreciate any help on how to solve this error.

Answer 1

selectedCellsData is an array of Subject. So you should pick an item from the array if that's what you need. So probably something like this

selectedCellsData.last.name.text = cell.nameLabel.text 

Answer 2

You said:

I created two lists of subjects and want to enable the user to add the selected subjects from the second list to the first. I have been trying to directly add the cells data which are distracted from another array with the same structure to the array from which the data for the first list are taken but as that did not work, I am now trying to work with an "in-between" dataset which is the one above. The lines here are the process of adding the cells' data to the "in-between"-array

So, let's say you have two arrays, one called allSubjects and another called selectedSubjects. And let's say you select a row in a table (and thus have an indexPath.row which indicates which row was selected in the table showing us allSubjects). Then you could do:

selectedSubjects.append(allSubjects[indexPath.row])

--

Unfortunately, this now begs the question if you unselect a row, how do you remove the Subject from selectedSubjects. You'd probably have to go down the road of making Subject conform to Equatable, use filter method, etc.

Possibly easier is to just keep track of the selected rows

var selectedRows = Set<Int>()

Then, when you select a row, you'd add a row entry:

selectedRows.insert(indexPath.row)

And when you unselect a row, you'd remove it

selectedRows.remove(indexPath.row)

For example, you could have cellForRowAtIndexPath set the appropriate accessory based upon the presence of the row in selectedRows:

override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCellWithIdentifier("AddSubjectCell", forIndexPath: indexPath) as! AddSubjectCell

    let subject = allSubjects[indexPath.row]

    cell.nameLabel.text = subject.name
    cell.semesterLabel.text = "Semester"
    cell.semesterNumberLabel.text = "\(subject.semester)"

    cell.accessoryType = selectedRows.contains(indexPath.row) ? .Checkmark : .None

    return cell
}

And then when the user selects a row, toggle its checkmark:

override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
    if selectedRows.contains(indexPath.row) {
        selectedRows.remove(indexPath.row)
    } else {
        selectedRows.insert(indexPath.row)
    }

    tableView.reloadRowsAtIndexPaths([indexPath], withRowAnimation: .Fade)
}

If you wanted, when you're all done, to get an array of selected subjects, you could then do something like:

var selectedSubjects = [Subject]()
for row in selectedRows {
    selectedSubjects.append(allSubjects[row])
}

--

Another approach is to add a selected property to the Subject class:

class Subject {
    var name: String
    var semester: Int
    var selected = false

    init(name: String, semester: Int) {
        self.name = name
        self.semester = semester
    }
}

Then cellForRowAtIndexPath can look at this property:

override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCellWithIdentifier("AddSubjectCell", forIndexPath: indexPath) as! AddSubjectCell

    let subject = allSubjects[indexPath.row]

    cell.nameLabel.text = subject.name
    cell.semesterLabel.text = "Semester"
    cell.semesterNumberLabel.text = "\(subject.semester)"

    cell.accessoryType = subject.selected ? .Checkmark : .None

    return cell
}

The didSelectRowAtIndexPath can just toggle it:

override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
    allSubjects[indexPath.row].selected = !allSubjects[indexPath.row].selected

    tableView.reloadRowsAtIndexPaths([indexPath], withRowAnimation: .Fade)
}

And then when you want the selected subjects, you can just filter them:

let selectedSubjects = allSubjects.filter { $0.selected }

There are lots of ways of skinning the cat.