相关疑难解决方法(0)

我正在尝试Swift书中的一些例子,即他们引入下标选项的矩阵示例.这是我的代码:

struct Matrix<T> {
    let rows: Int, columns: Int
    var grid: T[]

    var description: String {
        return "\(grid)"
    }

    init(rows: Int, columns: Int, initialValue: T) {
        self.rows = rows
        self.columns = columns
        grid = Array(count: rows * columns, repeatedValue: initialValue)
    }

    func indexIsValidForRow(row: Int, column: Int) -> Bool {
        return row >= 0 && row < rows && column >= 0 && column < columns
    }

    subscript(row: Int, column: Int) -> T {
        get {
            assert(indexIsValidForRow(row, column: column), "Index out …