子类化 NSInputStream，覆盖委托？

Question

我创建了一个 NSInputStream 子类，但是当它读取实际数据时，我得到了以下异常。

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -setDelegate: only defined for abstract class.  Define -[EventusCore.FileUploadStream setDelegate:]!'

我无法覆盖 NSStream 抽象类的以下属性：

unowned(unsafe) public var delegate: NSStreamDelegate?

这是我继承自 NSInputStream 的类

class InputStream : NSInputStream {

    private var currentStatus: NSStreamStatus  = .Closed

//    override var delegate: NSStreamDelegate?

    weak var delegate: NSStreamDelegate?

    override func open() {
        self.currentStatus = .Open
    }

    override func close() {
        self.currentStatus = .Closed
    }

    override var streamStatus: NSStreamStatus {
        return self.currentStatus
    }

    override var hasBytesAvailable: Bool {
        return self.currentStatus == .Open
    }

    // MARK: NSInputStream and CFReadStream abstract method overrides

    override func scheduleInRunLoop(aRunLoop: NSRunLoop, forMode mode: String) {

    }

    override func removeFromRunLoop(aRunLoop: NSRunLoop, forMode mode: String) {

    }

}

这是我得到的错误：

我做错了什么？使用 Swift 是否有可能？

Answer 1

找到了覆盖委托变量的合适方法

var localdelegate: NSStreamDelegate?

override var delegate: NSStreamDelegate? {
    set {
        self.localdelegate = newValue
    }
    get {
        return self.localdelegate
    }
}