How do I add a tuple to a Swift Array?

You have two issues. First problem, you're not creating an "array of tuples", you're creating an "optional array of tuples". To fix that, change this line:

var myStringArray: (String,Int)[]? = nil

to:

var myStringArray: (String,Int)[]

Second, you're creating a variable, but not giving it a value. You have to create a new array and assign it to the variable. To fix that, add this line after the first one:

myStringArray = []

...or you can just change the first line to this:

var myStringArray: (String,Int)[] = []

After that, this line works fine and you don't have to worry about overloading operators or other craziness. You're done!

myStringArray += ("One", 1)

Here's the complete solution. A whopping two lines and one wasn't even changed:

var myStringArray: (String,Int)[] = []
myStringArray += ("One", 1)

Swift 4 solution:

// init empty tuple array
var myTupleArray: [(String, Int)] = []

// append a value
myTupleArray.append(("One", 1))

If you remove the optional, it works fine, otherwise you'll have to do this:

var myStringArray: (String,Int)[]? = nil

if !myStringArray {
    myStringArray = []
}

var array = myStringArray!
array += ("One", 1)
myStringArray = array

You can never append an empty array, so you'll have to initialize it at some point. You'll see in the overload operator below that we sort of lazy load it to make sure that it is never nil.

You could condense this into a '+=' operator:

@assignment func += (inout left: Array<(String, Int)>?, right: (String, Int)) {

    if !left {
        left = []
    }

    var array = left!
    array.append(right.0, right.1)
    left = array

}

Then call:

var myStringArray: (String,Int)[]? = nil
myStringArray += ("one", 1)

I've ended up here multiple times due to this issue. Still not as easy as i'd like with appending onto an array of tuples. Here is an example of how I do it now.

Set an alias for the Tuple - key point

typealias RegionDetail = (regionName:String, constraintDetails:[String:String]?)

Empty array

var allRegionDetails = [RegionDetail]()

Easy to add now

var newRegion = RegionDetail(newRegionName, constraints)
allRegionDetails.append(newRegion)

var anotherNewRegion = RegionDetail("Empty Thing", nil)
allRegionDetails.append(anotherNewRegion)

Note: It's not work anymore if you do:

array += tuple 

you will get error what you need is :

array += [tuple]

I think apple change to this representation because it's more logical

 @assignment func += (inout left: Array<(String, Int)>?, right: (String, Int)) {
    if !left {
        left = []
    }   
    if left {
        var array = left!
        array.append(right.0, right.1)
        left = array
    }
}

var myStringArray: (String,Int)[]? = nil
myStringArray += ("x",1)

Thanks to comments:

import UIKit

@assignment func += (inout left: Array<(String, Int)>?, right: (String, Int)) {
    if !left {
        left = []
    }
    if left {
        var array = left!
        array.append(right.0, right.1)
        left = array
    }
}

class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()

        let interestingNumbers = [
            "Prime": [2, 3, 5, 7, 11, 13],
            "Fibonacci": [1, 1, 2, 3, 5, 8],
            "Square": [1, 4, 9, 16, 25],
        ]

        println("interestingNumbers: \(interestingNumbers)\n")
        var largest = 0

        var myStringArray: (String,Int)[]? = nil

        myStringArray += ("One", 1)

        var x = 0

        for (kind, numbers) in interestingNumbers {
            println(kind)
            for number in numbers {
                if number > largest {
                    largest = number
                }
                x++
                println("\(x)) Number: \(number)")
                myStringArray += (kind,number)
            } // end Number
        } // end Kind
        println("myStringArray: \(myStringArray)")
    }
}

The Output:

interestingNumbers: [Square: [1, 4, 9, 16, 25], Prime: [2, 3, 5, 7, 11, 13], Fibonacci: [1, 1, 2, 3, 5, 8]]

Square
1) Number: 1
2) Number: 4
3) Number: 9
4) Number: 16
5) Number: 25
Prime
6) Number: 2
7) Number: 3
8) Number: 5
9) Number: 7
10) Number: 11
11) Number: 13
Fibonacci
12) Number: 1
13) Number: 1
14) Number: 2
15) Number: 3
16) Number: 5
17) Number: 8

Array of tupules:

myStringArray: [(One, 1), (Square, 1), (Square, 4), (Square, 9), (Square, 16), (Square, 25), (Prime, 2), (Prime, 3), (Prime, 5), (Prime, 7), (Prime, 11), (Prime, 13), (Fibonacci, 1), (Fibonacci, 1), (Fibonacci, 2), (Fibonacci, 3), (Fibonacci, 5), (Fibonacci, 8)]