swift - 无法选择 pickerView 的默认值

Question

我有一个 pickerView，其中有很多主题。每个主题都是这样的类:

class subjects {
    var idSubject: String = "";
    var nameSubject: String = "";
    var notesSubject: String = "";
    var colorSubject: String = "";

    init(subjectId: String, subjectName: String, subjectNotes: String, subjectColor: String) {
        idSubject = subjectId
        nameSubject = subjectName
        notesSubject = subjectNotes
        colorSubject = subjectColor
    }

    func printSubject(){
        print(idSubject," - ",nameSubject," - ",notesSubject," - ",colorSubject)
    } 
}

我这样设置我的 pickerView:

public func numberOfComponents(in pickerView: UIPickerView) -> Int{
    return 1
}

public func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int{
    return MenuViewController.subjectsArray.count
}

func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
    self.view.endEditing(true)
    return MenuViewController.subjectsArray[row].nameSubject
}

我想选择特定主题的行，但我不能，因为使用 indexOf 它“无法将类型 'String' 的值转换为预期的参数类型 '(subjects) throws -> Bool'"在这行代码中:

if let index = MenuViewController.subjectsArray.indexOf("Matematica") {
    self.subjectsMenu.selectRow(index, inComponent: 0, animated: true)
}

有人可以帮助我吗？

Answer 1

if let index = MenuViewController.subjectsArray.index(where: {
    $0.nameSubject == "Matematica"
}) {
    self.subjectsMenu.selectRow(index, inComponent: 0, animated: true)
}