数组 – 2D数组扩展Swift 3.1.1

extension Array where Element: _ArrayProtocol,Element.Iterator.Element: Any {

    mutaTing func addObject(_ anObject : Element.Iterator.Element,toSubarrayATindex idx : int) {
        while self.count <= idx {
            let newSubArray = Element()
            self.append(newSubArray) 
        }

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

    func objectATindexPath(_ indexPath: IndexPath) -> Any {
        let subArray = self[indexPath.section]
        return subArraY[indexPath.row] as Element.Iterator.Element
    }
}

正如MarTin在Swift 3.1中所说的 in his answer here,_ArrayProtocol is no longer public,因此意味着你不能将它用作扩展中的约束. @H_675_19@ @H_675_19@在您的情况下,一个简单的替代方法是将Array的Element约束为RangeReplaceableCollection – 它们都定义了一个init()需求,意味着“空集合”,以及一个append(_ :)方法,以便将元素添加到集合中.

@H_675_19@

extension Array where Element : RangereplaceableCollection {

    typealias InnerCollection = Element
    typealias InnerElement = InnerCollection.Iterator.Element

    mutaTing func fillingAppend(
        _ newElement: InnerElement,toSubCollectionATindex index: IndeX) {

        if index >= count {
            append(contentsOf: repeatElement(InnerCollection(),count: index + 1 - count))
        }

        self[index].append(newElement)
    }
}

@H_675_19@另请注意,我们将append作为单个调用进行(使用append(contentsOf :),确保我们只需要调整外部数组的大小一次.

@H_675_19@对于从给定IndexPath获取元素的方法,您可以将内部元素类型约束为具有Int索引的Collection：

@H_675_19@

// Could also make this an extension on Collection where the outer Index is also an Int.
extension Array where Element : Collection,Element.Index == Int {

    subscript(indexPath indexPath: IndexPath) -> Element.Iterator.Element {
        return self[indexPath.section][indexPath.row]
    }
}

@H_675_19@请注意,我已经使它成为下标而不是方法,因为我觉得它更符合Array的API.

@H_675_19@你现在可以简单地使用这些扩展：

@H_675_19@

var arr = [[Int]]()

arr.fillingAppend(6,toSubCollectionATindex: 3)
print(arr) // [[],[],[6]]

let indexPath = IndexPath(row: 0,section: 3)
print(arr[indexPath: indexPath]) // 6

@H_675_19@虽然当然如果您事先知道外部数组的大小,fillAppend(_：toSubCollectionATindex :)方法是多余的,因为您可以通过以下方式创建嵌套数组：

@H_675_19@

var arr = [[Int]](repeaTing: [],count: 5)

@H_675_19@这将创建一个包含5个空[Int]元素的[[Int]]数组.