Swift 2D Array Extension

Question

I'm trying to make an Extension to the Array type so to be able to work with 2D arrays. In fact, I did this in Objective-C and the code below worked like a charm. But I really stuck in Swift.

extension Array {
    mutating func addObject(anObject : AnyObject, toSubarrayAtIndex idx : Int) {
        while self.count <= idx {
            let newSubArray = [AnyObject]()
            self.append(newSubArray)
        }

        var subArray = self[idx] as! [AnyObject]
        subArray.append(anObject)
    }

    func objectAtIndexPath(indexPath : NSIndexPath) -> AnyObject {
        let subArray = self[indexPath.section] as! Array
        return subArray[indexPath.row] as! AnyObject
    }
}

I get this error no matter what I do:

Error: Cannot invoke 'append' with an argument list of type '([AnyObject])'

I'd appreciate any help.

score 5 · Accepted Answer · answered Mar 25 '16 at 02:27

5

@brimstone's answer is close, but if I understand your question correctly, it is an array of [AnyObject], which means it should look like this:

extension Array where Element: _ArrayType, Element.Generator.Element: AnyObject {
    mutating func addObject(anObject : Element.Generator.Element, toSubarrayAtIndex idx : Int) {
        while self.count <= idx {
            let newSubArray = Element()
            self.append(newSubArray) // ERROR: Cannot invoke 'append' with an argument list of type '([AnyObject])'
        }

        var subArray = self[idx]
        subArray.append(anObject)
    }

    func objectAtIndexPath(indexPath: NSIndexPath) -> AnyObject {
        let subArray = self[indexPath.indexAtPosition(0)]
        return subArray[indexPath.indexAtPosition(1)] as Element.Generator.Element
    }
}

answered Mar 25 '16 at 02:27

Aaron Rasmussen

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43

You're brilliant! It worked but I really didn't get it all of that _ArrayType and Generator stuff. I have a lot to read I guess :) – Vitalii Vashchenko Mar 25 '16 at 10:21
In fact, there's an error I did make in the last two lines of the addObject method. The last line of the addObject method should look like this: self[idx].append(anObject) – Vitalii Vashchenko Mar 25 '16 at 18:50
I guess I need help with Swift 3 :) – Vitalii Vashchenko Jul 25 '16 at 22:51
Ca you post how this would look like in Swift 3, because I don't seem to be able to translate it .. – Stefan Stefanov May 24 '17 at 16:31

score 0 · Answer 2 · edited Mar 04 '20 at 22:47

You need to say what the array element type is in the extension. Try this:

extension _ArrayType where Generator.Element == AnyObject {
    mutating func addObject(anObject: AnyObject, toSubarrayAtIndex idx: Int) {
        while self.count <= idx {
            let newSubArray = [AnyObject]()
            self.append(newSubArray)
        }

        var subArray = self[idx] as! [AnyObject]
        subArray.append(anObject)
    }

    func objectAtIndexPath(indexPath: NSIndexPath) -> AnyObject {
        let subArray = self[indexPath.section] as! Array
        return subArray[indexPath.row] as! AnyObject
    }
}

From this question: Extend array types using where clause in Swift

Swift 2D Array Extension

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