ios - NSKeyedArchiver.archivedData 在 Swift 3 iOS 中不起作用

Question

当尝试在 iOS swift 中编码我的自定义对象时，从 Xcode 8.3 收到此错误

unrecognized selector sent to instance 0x60800166fe80 *** -[NSKeyedArchiver dealloc]: warning: NSKeyedArchiver deallocated without having had -finishEncoding called on it.

我的代码是这样的:

导入 UIKit 导入基金会

class Place: NSObject {

    func setCustomObject(CustomObject obj:Any,Key key:String) {

        let encodedObject : Data = NSKeyedArchiver.archivedData(withRootObject: obj)
        UserDefaults.standard.set(encodedObject, forKey: key)

    }
}

Answer 1

下面是一个如何使对象符合 NSCoding 的示例。基本上你需要提供两种方法的实现 - required convenience init?(coder decoder: NSCoder) 和 encode(with aCoder: NSCoder)

class Book: NSObject, NSCoding {
  var title: String?
  var pageCount: Int?

  // Memberwise initializer
  init(title: String,pageCount: Int) {
   self.title = title
   self.pageCount = pageCount
  }

  // MARK: NSCoding


  // Here you will try to initialize an object from archve using keys you did set in `encode` method.
  required convenience init?(coder decoder: NSCoder) {
    guard let title = decoder.decodeObject(forKey: "title") as? String else { return nil }

    self.init(title: title, pageCount: decoder.decodeInteger(forKey: "pageCount"))
  }

  // Here you need to set properties to specific keys in archive
  func encode(with aCoder: NSCoder) {
    aCoder.encode(self.title, forKey: "title")
    aCoder.encodeCInt(Int32(self.pageCount), forKey: "pageCount")
  }
}

此外，我建议将您的 setCustomObject 方法更改为:

func setCustomObject(obj:NSCoding, key:String) {
  let encodedObject : Data = NSKeyedArchiver.archivedData(withRootObject: obj)
  UserDefaults.standard.set(encodedObject, forKey: key)
}

这样编译器会阻止您向 NSKeyedArchiver 传递一个不符合 NSCoding 协议(protocol)的对象。

如果您不想在 init 方法中提供所有属性，您可以使用默认值:

init(title : String? = nil, pageCount: Int? = nil){
  self.title = title
  self.pageCount = pageCount
}

现在你可以在没有任何属性的情况下初始化你的对象。就像那个Book()