ios - Swift 中的 NSCoding 没有正确归档数据？

Question

总的来说，我对 iOS 开发还比较陌生，但我正在编写这个应用程序。

我有自定义对象“学期”、“类(class)”和“作业”。学期包含类(class)数组，类(class)包含作业数组。我能够正确存档学期和类(class)信息，但由于某种原因无法读取作业信息。

学期:

required init?(coder aDecoder: NSCoder) {
    self.name = ""

    super.init()

    if let archivedName = aDecoder.decodeObject(forKey: "name") as? String {
        name = archivedName
    }
    if let archivedCourses = aDecoder.decodeObject(forKey: "courses") as? [Course] {
        courses = archivedCourses
    }
}

func encode(with aCoder: NSCoder) {
    aCoder.encode(name, forKey: "name")
    aCoder.encode(courses, forKey: "courses")
}

类(class):

required init?(coder aDecoder: NSCoder) {
    self.name = ""
    super.init()

    if let archivedName = aDecoder.decodeObject(forKey: "courseName") as? String {
        name = archivedName
    }
    if let archivedAssignments = aDecoder.decodeObject(forKey: "assignments") as? [Assignment] {
        assignments = archivedAssignments
    }
}

func encode(with aCoder: NSCoder) {
    aCoder.encode(name, forKey: "courseName")
    aCoder.encode(assignments, forKey: "assignments")

作业:

required init?(coder aDecoder: NSCoder) {
    self.name = ""
    self.grade = 0
    self.weight = 0
    super.init()

    if let archivedName = aDecoder.decodeObject(forKey: "assignmentName") as? String, let archivedGrade = aDecoder.decodeObject(forKey: "assignmentGrade") as? Int, let archivedWeight = aDecoder.decodeObject(forKey: "assignmentWeight") as? Int {
        name = archivedName
        grade = archivedGrade
        weight = archivedWeight
    }
}

func encode(with aCoder: NSCoder) {
    aCoder.encode(name, forKey: "assignmentName")
    aCoder.encode(grade, forKey: "assignmentGrade")
    aCoder.encode(weight, forKey: "assignmentWeight")
}

我不确定为什么，但是当我尝试解码对象时无法读取分配详细信息。

Answer 1

我通常这样解码Int

if decoder.containsValue(forKey: "teamNumber"){
    self.teamNumber = decoder.decodeInteger(forKey: "teamNumber")
}

翻译成你的问题会是这样的，改变你的Assignment类的init?(coder aDecoder: NSCoder)方法

required init?(coder aDecoder: NSCoder) {

    self.name = ""
    self.grade = 0
    self.weight = 0
    super.init()

    if let archivedName = aDecoder.decodeObject(forKey: "assignmentName") as? String{
      self.name = archivedName
    } 

    if decoder.containsValue(forKey: "assignmentGrade"){
        self.grade = decoder.decodeInteger(forKey: "assignmentGrade")
    }

    if decoder.containsValue(forKey: "assignmentWeight"){
        self.weight = decoder.decodeInteger(forKey: "assignmentWeight")
    }

}

希望对你有帮助