If you’re not familiar with the Fibonacci sequence, the gist is that each number is the sum of the two numbers before it, starting from `0`

and `1`

.

Step by step, it would look like this:

- Take the first two numbers:
`0`

and`1`

Our series looks like this:`0, 1`

- Add them and add the result to our series:
`0`

+`1`

=`1`

Now our series looks like this:`0, 1, 1`

- In order to get the next number, you add the two numbers before it. We’ll put in an
`x`

to represent the number we want:`0, 1, 1, x`

To get`x`

, we take`1`

, and`1`

and add them:`2`

. Now our series looks like this:

`0, 1, 1, 2`

- Chugging along, we want the next number:

`0, 1, 1, 2, x`

So we take`2`

and`1`

, which is`3`

and that gets us to

`0, 1, 1, 2, 3`

- Take
`3`

and`2`

to get`5`

:

`0, 1, 1, 2, 3, 5`

- Take
`5`

and`3`

to get`8`

:

`0, 1, 1, 2, 3, 5, 8`

and so on.

As a function it looks like this:

```
// Get the Fibonacci number at num
func fibonacci(num: Int) -> Int {
if num == 0 {
return 0
}
if num < 1 {
return 1
}
return fibonacci(num: num - 1) + fibonacci(num: num - 2)
}
```

We can get a sequence by calling the above function in a loop:

```
// Get the first num numbers in the Fibonacci sequence
func fibonacciSequence(num: Int) -> [Int] {
var series = [Int]()
for i in 0…num - 1 {
let fibNum = fibonacci(num: i)
series.append(fibNum)
}
return series
}
```

So if we feed `7`

to our function, we should get a return value of `[0, 1, 1, 2, 3, 5, 8]`