How to compare the String value of a [[String]] to a String?

Question

I want to be able to compare values from the [String] level instead of the String level. Here's what I mean:

var connectedNames:[[[String]]] = [[[]]]

for var row: Int = 0; row < connectedNames[0].count; row++ {
    if self.connectedNames[0][row] as! String == "asdf" {

    }
}

But the cast here from [String] to String fails so I can't make this value comparison.

So the main problem is this: Is there anyway to compare the String value of a [[String]] to a String? In other words, the String value that I get from indexing connectedNames like so connectedNames[0][0] == "Some String"?

Just a suggestion: Perhaps instead of nesting arrays so many levels, you could define a class or struct that does what you are looking to achieve, complete with a method that performs the comparison you're after, get it working, and forget about the implementation details. Your future self will thank you down the line. — Nicolas Miari
– Nicolas Miari, Commented May 2, 2016 at 1:53
@NicolasMiari Thank you for your suggestion. But I am so noob that I don't really know how to use classes and structures effectively. So I have a vague understanding of you meaning. I hope one day, I'll get to see how to use them correctly in other people's code! — aejhyun
– aejhyun, Commented May 3, 2016 at 10:29

Christopher Harris · Accepted Answer · 2016-05-02 01:20:52Z

2

You can only compare [[String]] to String by using the subscript method of the Array to access the inner element. This would work:

func compare() -> Bool {
    let arr: [[String]] = [["foo"]]
    let str: String = "foo"

    guard let innerArr = arr[0] else {
      return false
    }

    guard let element = innerArr[0] else {
      return false
    }

    return element == str
}

edited May 2, 2016 at 1:20

answered May 2, 2016 at 1:15

Christopher Harris

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3 Comments

boidkan Over a year ago

The triple '===' is to compare of that are the exact same object not if their value is the same

aejhyun Over a year ago

Thank you @ChristopherHarris for your answer! I truly appreciate your help. I am trying to understand it right now. One thing though, why do you have the guard? Is that necessary? Or is it just safer coding?

Christopher Harris Over a year ago

Better coding. Swift prefers guard over nested conditionals for readability. Please accept this answer too, thanks!

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