Swift语言:nil检查,如果是,则实例化新对象

Question

有什么方法可以简化这个:

var unloadedImagesRows = [String:[Int]]()

private func addToUnloadedImagesRow(row: Int, forLocation:String!) {
    if unloadedImagesRows[forLocation] == nil {
                    unloadedImagesRows[forLocation] = [Int]()
    }
    unloadedImagesRows[forLocation]!.append(row)
}

Swift是否有一种简单的方法可以检查nil,如果是,则创建一个新对象,所有后续使用都引用该对象？

Answer 1

您可以将其简化为一行:

private func addToUnloadedImagesRow(row: Int, forLocation:String!) {
    unloadedImagesRows[forLocation] = (unloadedImagesRows[forLocation] ?? []) + [row]
}