swift NSCoding 不工作

Question

我在 Swift 中使用 NSCoding 时遇到问题。我试图实现该协议(protocol)，但每当我调用我的 save() 方法时都会发生崩溃。 Xcode 在 encodeWithCoder 中将我拉上线。这是我的代码，任何建议都会随之而来。

class CourseList: NSObject, NSCoding {
    ...

    init(coder aDecoder: NSCoder!){
        super.init()
        if aDecoder != nil {
            self.courses = aDecoder.decodeObjectForKey("courses") as Dictionary<String,course>
        }
    }

    func encodeWithCoder(aCoder: NSCoder!) {
        aCoder!.encodeObject(self.courses, forKey: "courses") // EXC_BAD_INSTRUCTOIN


    }
}

我编写了 save() 和 load() 来调用 ViewController。

func save() {
    var archivedObject = NSKeyedArchiver.archivedDataWithRootObject(History)  //NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    var defaults = NSUserDefaults.standardUserDefaults()  //[defaults setObject:archivedObject forKey:<key_for_archived_object>];
    defaults.setObject(History.courses, forKey: "courses")
    defaults.synchronize()
}

func load() {
    var defaults = NSUserDefaults.standardUserDefaults()  // NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    var archivedObject = defaults.objectForKey("courses") as NSData  // NSData *archivedObject = [defaults objectForKey:<key_for_archived_object>];
    History = NSKeyedUnarchiver.unarchiveObjectWithData(archivedObject) as Dictionary<String,course>   //<your_class> *obj = (<your_class> *)[NSKeyedUnarchiver unarchiveObjectWithData:archivedObject];

}

Answer 1

自从提出这个问题后，Swift 发生了相当多的变化。我无法重现您看到的错误，但我能够使用以下代码让 NSCoding 与 Swift 1.0 一起工作。

class CourseList: NSObject, NSCoding
{
    var myCourses: Dictionary<String, String>?

    override init() {}

    required init(coder aDecoder: NSCoder) {
        self.myCourses  = aDecoder.decodeObjectForKey("myCourses") as? Dictionary
    }

    func encodeWithCoder(aCoder: NSCoder) {
        if let courses = self.myCourses{
            aCoder.encodeObject(courses, forKey: "myCourses")
        }
    }

    func populateCourses() {
        self.myCourses = ["cs101": "Hello World"]
    }

    func save() {
        let data = NSKeyedArchiver.archivedDataWithRootObject(self)
        NSUserDefaults.standardUserDefaults().setObject(data, forKey: "courseList")
    }

    func clear() {
        NSUserDefaults.standardUserDefaults().removeObjectForKey("courseList")
    }

    class func loadSaved() -> CourseList? {
        if let data = NSUserDefaults.standardUserDefaults().objectForKey("courseList") as? NSData {
            return NSKeyedUnarchiver.unarchiveObjectWithData(data) as? CourseList
        }
        return nil
    }
}

加载已保存的实例或在需要时创建新实例

    // Try loading a saved version first
    if let courseLs = CourseList.loadSaved() {
        println("loaded Save CourseList")
    } else {
        // Create a new Course List
        let courseLs: CourseList = CourseList()
        courseLs.populateCourses()
        courseLs.save()
    }