'[[String]]' to expected argument type '[String]'

Question

I am getting the error in a project of mine: ​

Cannot convert value of type '[[String]]' to expected argument type '[String]'​

​I totally understand this error; I have a String within an Array within an Array that cannot be casted as a String within an Array. But the issue I am running into is a work around. What I am trying to do is return a string of titles as buttons, which is casted into rows of 7, which is cast into a group of 4 rows. So the buttons are casted from a string to UIButton, the Rows are arrays casted as UIViews, and the groups are arrays casted as UIViews. But when I go to cast the group this is when I get the error. Below is the relative code, and any help would be much appreciated (sorry for the bad english):

let buttonTitles1 = ["1","2","3","4","5","6","7"]
let buttonTitles2 = ["1","2","3","4","5","6","7"]
let buttonTitles3 = ["1","2","3","4","5","6","7"]
let buttonTitles4 = ["1","2","3","4","5","6","7"]

let row1 = buttonTitles1
let row2 = buttonTitles2
let row3 = buttonTitles3
let row4 = buttonTitles4

let matrixTitle1 = [buttonTitles1, buttonTitles1, buttonTitles1, buttonTitles1]
let matrixTitle2 = [buttonTitles1, buttonTitles1, buttonTitles1, buttonTitles1]

let matrix1 = createArraysOfButtons(matrixTitle1)
let matrix2 = createArraysOfButtons(matrixTitle2)

keyBoardKeys.addSubview(matrix1) //ERROR
keyBoardKeys.addSubview(matrix2) //ERROR

//BUTTON FUNCTION

func createButtonWithTitle(title: String) -> UIButton {

    let button = UIButton(type:.System) as UIButton
    button.translatesAutoresizingMaskIntoConstraints = false
    button.setTitle(title, forState: .Normal)
    button.sizeToFit()
    button.titleLabel!.font = UIFont.systemFontOfSize(15)
    button.backgroundColor = UIColor.greenColor()
    button.setTitleColor(UIColor.whiteColor(), forState: .Normal)
    print("BUTTON")
    return button
}

//ROW FUNCTION

func createRowOfButtons(buttonTitles: [String]) -> UIView {

    var buttons = [UIButton]()
    let keyboardRowView = UIView()
    keyboardRowView.translatesAutoresizingMaskIntoConstraints = false

    for buttonTitle in buttonTitles{

        let button = createButtonWithTitle(buttonTitle as String)
        buttons.append(button)
        keyboardRowView.addSubview(button)
    }

    addIndividualButtonConstraints(buttons, mainView: keyboardRowView)
    print("ROW")
    return keyboardRowView
}

//MATRIX FUNCTION

func createArraysOfButtons (rowTitles: [String]) -> UIView {

    var rows = [UIView]()
    let keyArrayView = UIView()

    for rowTitle in rowTitles {
            let row = createRowOfButtons([rowTitle])
            rows.append(row)
            keyArrayView.addSubview(row)
    }

    addConstraintsToInputView(rows, mainView: keyArrayView)
    print("MATRIX")
    return keyArrayView
}

Answer 1

Your problem is with this function:

func createArraysOfButtons (rowTitles: [String]) -> UIView {

    var rows = [UIView]()
    let keyArrayView = UIView()

    for rowTitle in rowTitles {
            let row = createRowOfButtons([rowTitle])
            rows.append(row)
            keyArrayView.addSubview(row)
    }

    addConstraintsToInputView(rows, mainView: keyArrayView)
    print("MATRIX")
    return keyArrayView
}

It should take an array of arrays and it instead takes a simple array, change your function to this:

func createArraysOfButtons (rowTitles: [[String]]) -> UIView {

var rows = [UIView]()
let keyArrayView = UIView()

for rowTitle in rowTitles {
        let row = createRowOfButtons(rowTitle) // remove square brakets
        rows.append(row)
        keyArrayView.addSubview(row)
}

addConstraintsToInputView(rows, mainView: keyArrayView)
print("MATRIX")
return keyArrayView
}

Think about what your working with, you've got an [String]:

let buttonTitles4 = ["1","2","3","4","5","6","7"]

and you're storing it into another array making it [[String]]

let matrixTitle1 = [buttonTitles1, buttonTitles1, buttonTitles1, buttonTitles1]

Then you're calling your function

let matrix1 = createArraysOfButtons(matrixTitle1)