Get values from complex Array of Dictionary in Swift2

Question

I'm displaying a dictionary as UITableView. I did this very easily in Objective- c . But now in swift, I cannot get values from array of dictionary. When I try to get values in the tableView:cellForRowAtIndexPath the precompiler throw error like

Cannot convert value of type "AnyObject?!" to specified type 'Array'

or like in this example below

Cannot convert value of type "AnyObject?!" with an idnex of type 'int'

var cellArray = []

override func viewDidLoad() {
    cellArray = [
        [
            "section" : "Melody",
            "rows" :
                [
                    [
                        "title" : "Wi-Fi / Pairing",
                        "icon" : "",
                        "action" : "actionConnectSpeaker"
                    ],
                    [
                        "title" : "Sound",
                        "icon" : "",
                        "action" : "actionConnectSpeaker"
                    ]
                ]
        ],

        [
            "section" : "Music",
            "rows" :
                [
                    [
                        "title" : "Add a new account",
                        "icon" : "",
                        "action" : "actionAddAccount"
                    ]
                ]
        ]
    ]
}

...

override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {

    let cell = UITableViewCell(style: UITableViewCellStyle.Value2, reuseIdentifier: nil)

    cell.textLabel?.text = cellArray[indexPath.section]["rows"][indexPath.row]["title"]


    return cell
}

I conclude we cannot do like this... I find any example. I probably not understand something about Types in Swift ...

vadian · Accepted Answer · 2015-10-22 09:21:48Z

2

In Swift you have to downcast AnyObject types if you want to call functions like objectAtIndex: or objectForKey: what subscripting actually does.

let section = cellArray[indexPath.section]
let rows = section["rows"] as! [[String:String]]
cell.textLabel?.text = rows[indexPath.row]["title"]

answered Oct 22, 2015 at 9:21

vadian

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Comments

yuhua · Accepted Answer · 2015-10-22 09:23:37Z

0

Simply doing this if you're sure there's no nil value:

cell.textLabel?.text = cellArray[indexPath.section]["rows"]![indexPath.row]["title"]

answered Oct 22, 2015 at 9:23

yuhua

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1 Comment

Damien Romito Over a year ago

check the answer above. Your answer answers to an other problem

katleta3000 · Accepted Answer · 2015-10-22 09:25:26Z

0

If you want to do it safely (if any object can be nil or the other type, you should use if let:

if let dict = cellArray[indexPath.section] as? [String : AnyObject],
    rows = dict["rows"] as? [AnyObject], 
    result = rows[indexPath.row] as? [String : AnyObject],
    title = result["title"] {
    cell.textLabel?.text = title
}

answered Oct 22, 2015 at 9:25

katleta3000

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Comments

Cosyn · Accepted Answer · 2015-10-22 11:10:16Z

You should generally avoid collections with elements of different types in Swift. Your section data is a dictionary, the value of "section" key is a string while the value of "rows" key is an array. Try to replace this dictionary with a tuple.

var cellArray = [(String, [[String: String]])]()

override func viewDidLoad() {
    cellArray = [
        (
            "Melody",
            [
                [
                    "title" : "Wi-Fi / Pairing",
                    "icon" : "",
                    "action" : "actionConnectSpeaker"
                ],
                [
                    "title" : "Sound",
                    "icon" : "",
                    "action" : "actionConnectSpeaker"
                ]
            ]
        ),

        (
            "Music",
            [
                [
                    "title" : "Add a new account",
                    "icon" : "",
                    "action" : "actionAddAccount"
                ]
            ]
        )
    ]
}

override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {

    let cell = UITableViewCell(style: UITableViewCellStyle.Value2, reuseIdentifier: nil)

    cell.textLabel?.text = cellArray[indexPath.section].1[indexPath.row]["title"]

    return cell
}

This way Swift's type system can help you make sure you are using the right type, no force downcasting is needed.

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