我在Swift中使用NSCoding有困难。我尝试实现协议，但是当我调用save()方法时，我会遇到崩溃。 Xcode把我拉到了encodeWithCoder的行上。这是我的代码，任何建议都会顺理成章。
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];
}
自从提出这个问题以来，Swift已经有所改变了。我无法重现你所看到的错误，但是我能够使用下面的代码让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
}
}
加载保存的实例，或者根据需要创建一个新的实例
// 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()
}
