无法应用 Swift 3.0 二元运算符“==" [英] Swift 3.0 binary operator '==' cannot be applied

问题描述

在 Swift 3.0 中，当我尝试比较 [[String: AnyObject]] 和 [[String: AnyObject]] 类型的两个项目时，我遇到了一个奇怪的错误！.所以其中一个是强制展开的，另一个不是.

In Swift 3.0 I'm getting a weird error when I try to compare two items which are of type [[String: AnyObject]] and [[String: AnyObject]]!. So one of them is force unwrapped and the other is not.

所以比较如下:

let smth: [[String: AnyObject]] = [["key": "Value"]]
let smth2: [[String: AnyObject]]?  = someFunctionThatReturnsAnOptionalArrayOfDictionaries()

if smth == smth2! {
    print("Equal")
}

错误说:二元运算符=="不能应用于[[String : AnyObject]]"和[[String : AnyObject]]!"类型的操作数

在 Swift 3 中执行此操作的正确方法是什么?

What is the correct way to do this in Swift 3?

推荐答案

这有点棘手，因为你不能直接比较数组或字典(没有重载运算符).

It is a little tricky, since you can't directly compare arrays or dictionaries (without overloading operators).

您可能面临的另一个问题是可选和非可选的比较，这在 Swift 3 中已被删除(仅适用于 < 和 >，== 和 != 仍然有效！):

Another problem you could be facing is optional and non-optional comparisons, which was removed in Swift 3 (only for < and >, == and  != still work!):

Swift Evolution - 提案 #0121

我所做的工作是首先用 if let 解开可选项，然后我将它们与 elementsEqual 进行比较，首先是数组，然后是字典.

What I did to make it work was first unwrap the optional with if let then I compared them with elementsEqual, first the array, then the dictionary.

let smth: [[String: AnyObject]] = [["key": "Value" as AnyObject]]
let smth2: [[String: AnyObject]]?  = nil

if let smth2 = smth2, smth.elementsEqual(smth2, by: { (obj1, obj2) -> Bool in
    return obj1.elementsEqual(obj2) { (elt1, elt2) -> Bool in
        return elt1.key == elt2.key && elt1.value === elt2.value
    }

}) {
    print("Equal")
}

另一个问题是，由于您使用 AnyObject 作为值，因此无法直接比较它们.这就是为什么我使用 === 来检查比较对象的引用是否相同.不确定这是否是您想要的.

Another problem is, since you are using AnyObject as value, you can't compare them directly. Thats why I used === which checks if the reference of comparing objects is the same. Not sure if this is what you wanted.

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