Swift - 不能转换为'NativeObject'

Question

我有以下功能，它在Xcode 6 beta 2中运行良好

func connectPotentially(node: MazeNode)
{
    if node.position != self.position && self.potentialPaths[node.position] == nil {
        self.potentialPaths[node.position] = node
        node.potentialPaths[self.position] = self

        println("Potential path between \(self.position.level)x\(self.position.index) and \(node.position.level)x\(node.position.index)")
    }
}

然而，在Xcode 6 beta 3中，我收到以下错误：

我不知道这是什么意思。有什么想法吗？也许是一个错误？

这是文件的完整转储：

import Foundation


struct MazeNodePosition : Hashable, Equatable {
var level: Int
var index: Int

var hashValue: Int {
    get {
        return level * 0xffff + index
    }
}
}

@infix func ==(left: MazeNodePosition, right: MazeNodePosition) -> Bool
{
    return left.level == right.level && left.index == right.index
}


class MazeNode {

let position: MazeNodePosition

var potentialPaths: Dictionary<MazeNodePosition, MazeNode> = [:]
var paths: Dictionary<MazeNodePosition, MazeNode> = [:]
var visited: Bool = false


init(position: MazeNodePosition)
{
    self.position = position
}


func connectPotentially(node: MazeNode)
{
    if node.position != self.position && self.potentialPaths[node.position] == nil {
        self.potentialPaths[node.position] = node
        node.potentialPaths[self.position] = self

        println("Potential path between \(self.position.level)x\(self.position.index) and \(node.position.level)x\(node.position.index)")
    }
}


func tryConnecting(node: MazeNode) -> Bool
{
    if node.position != self.position && self.paths[node.position] == nil && !node.visited {
        self.paths[node.position] = node
        node.paths[self.position] = self
        node.visited = true
        self.visited = true

        println("Path between \(self.position.level)x\(self.position.index) and \(node.position.level)x\(node.position.index)")

        return true
    }

    return false
}
}

Answer 1

简单修复if语句：

self.paths[node.position] == nil

应写成：

self.paths[node.position]