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

Question

I have an array of arrays and need to filter out one of the specific arrays in it. However, when using the following code, I get the issue "Binary operator '!=' cannot be applied to two '[[String]]' operands".

var arrayOfArrays = [[[String]]]()
var specificArray = [[String]]()

arrayOfArrays = arrayOfArrays.filter{$0 != specificArray}

I think this used to work like half a year ago...

specificArray is an array of an array of strings while arrayOfArrays is more like an array of arrays of arrays. — Julian Lee, Mar 22 '17 at 10:28
Look at this answer about comparing arrays http://stackoverflow.com/questions/27567736/compare-arrays-in-swift — Hunaid Hassan, Mar 22 '17 at 10:30
Thank you for the responses. Hunaid, I ran into that post when I was researching my issue but had not managed to find an appropriate solution to my issue with it. Am I missing something? — Julian Lee, Mar 22 '17 at 10:31
@JulianLee I think having an `Array>>` in your code is very likely a sign something is wrong with your code. What are you trying to achieve? — overactor, Mar 22 '17 at 10:34
I need to store an array of strings in categories which can be arranged into several larger categories and put into a single, accessible array. Is there a more efficient way to carry this data? — Julian Lee, Mar 22 '17 at 10:42

score 1 · Accepted Answer · edited May 23 '17 at 12:00

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As mentioned in the comments, Swift Arrays don't conform to Equatable so [[T]] != [[T]] does not work because it requires [T] to be Equatable. You could use elementsEqual(_:by:) instead, which allows comparing elements using a custom equality function, without being Equatable:

arrayOfArrays = arrayOfArrays.filter { !$0.elementsEqual(specificArray, by: ==) }

(Note: Thanks to SE-0143 "Conditional conformances", this workaround is no longer needed once Swift 4 is released.)

edited May 23 '17 at 12:00

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answered Mar 22 '17 at 10:32

kennytm

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This is exactly what I was looking for. I see the part where I was confused regarding the other post, thank you for the explanation! – Julian Lee Mar 22 '17 at 10:36

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

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