swift - 比较强制展开的可选数组

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

数组可以比较与==如果元素类型是 Equatable :

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

但都不是 ImplicitlyUnwrappedOptional<Wrapped>也不Optional<Wrapped>符合 Equatable , 即使底层类型 Wrapped

可能的选项是(假设 VMVideo 符合 Equatable ):

• 更改您的代码，使 videos和 shuffledVideos是 [VMVideo]数组而不是 [VMVideo!] .

• 按元素比较数组:

  XCTAssert(videos.count == shuffledVideos.count
      && !zip(videos, shuffledVideos).contains {$0 != $1 })
  

• 定义一个 ==隐式解包等式数组的运算符元素:

  func ==<Element : Equatable> (lhs: [Element!], rhs: [Element!]) -> Bool {
      return lhs.count == rhs.count && !zip(lhs, rhs).contains {$0 != $1 }
  }