title: How to find the index of an item in a multidimensional array swiftily?
body: <p>Let's say I have this array:</p>
  
  <pre><code>let a = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
  </code></pre>
  
  <p>Now I want something like this:</p>
  
  <pre><code>public func indicesOf(x: Int, array: [[Int]]) -&gt; (Int, Int) {
      ...
  }
  </code></pre>
  
  <p>so that I can call it like this:</p>
  
  <pre><code>indicesOf(7, array: a) // returns (2, 0)
  </code></pre>
  
  <p>Of course, I can use:</p>
  
  <pre><code>for i in 0..&lt;array.count {
      for j in 0..&lt;array[i].count {
          if array[i][j] == x {
              return (i, j)
          }
      }
  }
  </code></pre>
  
  <p>But that is not even close to swifty!</p>
  
  <p>I want a way to do this which is swifty. I think maybe I can use <code>reduce</code> or <code>map</code>?</p>