Question

我正在写一个测试：

    func test_arrayFromShufflingArray() {

        var videos = [MockObjects.mockVMVideo_1(), MockObjects.mockVMVideo_2(), MockObjects.mockVMVideo_3()]
        let tuple = ShuffleHelper.arrayFromShufflingArray(videos, currentIndex:1)

        var shuffledVideos = tuple.0
        let shuffleIndexMap = tuple.1


        // -- test order is different
        XCTAssert(videos != shuffledVideos, "test_arrayFromShufflingArray fail")
    }

但是在最后一行我得到了最后一行：

Binary operator '!=' cannot be applied to two '[VMVideo!]' operands

Answer 1

如果元素类型为==，则可以将与Equatable进行比较：

/// Returns true if these arrays contain the same elements.
public func ==<Element : Equatable>(lhs: [Element], rhs: [Element]) -> Bool

但ImplicitlyUnwrappedOptional<Wrapped>和Optional<Wrapped>都不符合Equatable，即使是Wrapped 基础类型VMVideo。

可能的选项是（假设Equatable符合videos）：

更改您的代码，以便shuffledVideos和[VMVideo]为 [VMVideo!]数组而不是XCTAssert(videos.count == shuffledVideos.count && !zip(videos, shuffledVideos).contains {$0 != $1 })。
按元素比较数组：
```
==
```
为隐式展开的equatable数组定义func ==<Element : Equatable> (lhs: [Element!], rhs: [Element!]) -> Bool { return lhs.count == rhs.count && !zip(lhs, rhs).contains {$0 != $1 } }运算符元素：
```
{{1}}
```

Answer 2

Swift无法告诉如何比较两个数组，看它们的内容是否相同，除非它知道如何比较各个元素。因此，您需要在班级上实施==功能并采用Equatable：

extension VMVideo: Equatable {
    // nothing goes here, == function has to be at global scope
}

func ==(lhs: VMVideo, rhs: VMVideo) -> Bool {
    // Up to you to determine what equality means for your object, e.g.:
    return lhs.essentialProperty1 == rhs.essentialProperty1 &&
        lhs.essentialProperty2 == rhs.essentialProperty2
}

编辑要说明它与NSObject的互动方式以及对您的环境进行问题排查，请确认以下内容：

class UnderstandsEqual: NSObject {}
let ok1: [UnderstandsEqual] = [UnderstandsEqual(), UnderstandsEqual()]
let ok2: [UnderstandsEqual] = [UnderstandsEqual(), UnderstandsEqual()]
ok1 == ok2 // no problem, evaluates to true

class DoesntUnderstand {}
let bad1: [DoesntUnderstand] = [DoesntUnderstand(), DoesntUnderstand()]
let bad2: [DoesntUnderstand] = [DoesntUnderstand(), DoesntUnderstand()]
bad1 == bad2 // produces a compile-time error

Answer 3

Martin R的答案是更好的答案，但出于这个特定目的，我刚刚转换为NSArray，并且能够在Swift中使用==运算符：

func test_arrayFromShufflingArray() {

    let videos = [MockObjects.mockVMVideo_1(), MockObjects.mockVMVideo_2(), MockObjects.mockVMVideo_3()]
    let videosNSArray: NSArray =  videos.map { $0 }
    let tuple = ShuffleHelper.arrayFromShufflingArray(videos, currentIndex:1)

    let shuffledVideos = tuple.0
    let shuffledVideosNSArray: NSArray =  shuffledVideos.map { $0 }


    // -- test order is different
    XCTAssert(videosNSArray != shuffledVideosNSArray, "test_arrayFromShufflingArray fail")


    // -- test elements are the same
    let set = NSSet(array: videos)
    let shuffledSet = NSSet(array: shuffledVideos)
    XCTAssert(set == shuffledSet, "test_arrayFromShufflingArray fail")
}

比较力量打开的选项数组

3 个答案: