Swift Equatable Protocol [英] Swift Equatable Protocol

问题描述

我正在为Swift提供本教程： https://www.raywenderlich.com/125311/make-game-like-candy-crush-spritekit-swift-part-1 并遇到此代码：

I was folling this tutorial for Swift: https://www.raywenderlich.com/125311/make-game-like-candy-crush-spritekit-swift-part-1 and came across this code:

func == (lhs: Cookie, rhs: Cookie) -> Bool {
    return lhs.column == rhs.column && lhs.row == rhs.row
}

我写的确是这样，但Xcode是给出我的这些错误：

I wrote exactly that, but Xcode is giving my these errors:

Consecutive declarations on a line must be separated by ';'
Expected declaration operators are only allowed at global scope

我从apple的文档中找到了这段代码： https://developer.apple.com/documentation/swift/equatable

I found this code from apple's documentation: https://developer.apple.com/documentation/swift/equatable

这和我写的很相似。怎么了？这对我来说似乎是个错误。我正在使用Xcode 6 Beta 2

Which is very similar to what I wrote. Whats wrong? This seems like a bug to me. I am using Xcode 6 Beta 2

这是我的整个Cookie类：

This is my whole Cookie class:

class Cookie: Printable, Hashable {
    var column: Int
    var row: Int
    let cookieType: CookieType
    let sprite: SKSpriteNode?

    init(column: Int, row: Int, cookieType: CookieType) {
        self.column = column
        self.row = row
        self.cookieType = cookieType
    }

    var description: String {
        return "type:\(cookieType) square:(\(column),\(row))"
    }

    var hashValue: Int {
        return row * 10 + column
    }

    func ==(lhs: Cookie, rhs: Cookie) -> Bool {
        return lhs.column == rhs.column && lhs.row == rhs.row
    }
}

推荐答案

移动此功能

func == (lhs: Cookie, rhs: Cookie) -> Bool {
    return lhs.column == rhs.column && lhs.row == rhs.row
}

在cookie类之外。这种方式很有意义，因为它在两个Cookie上使用时会覆盖全局范围内的==运算符。

Outside of the cookie class. It makes sense this way since it's overriding the == operator at the global scope when it is used on two Cookies.

这篇关于Swift Equatable Protocol的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！