Swift-替換嵌套結構中的值

Question

我需要變異深度未知的嵌套字典。

我意識到當我實際上需要引用類型（“ NSMutable”）時，swift中的結構就是值類型

但是我注意到，如果使用dot（。）語法訪問嵌套結構，則可以直接更新值，而無需重新分配給原始的“父級”。

例如，對於嵌套數組：

var l1 = ["a0","b0"]
var l2 = ["a1","b1"]
var list = [l1,l2]
print(list)
>>[["a0", "b0"], ["a1", "b1"]]


// I can mutate the nested structs by using dot(.) syntax
// mutate the zero indexed nested array:
list[0].insert("x0", atIndex: 0)
print(list)
>> [["x0", "a0", "b0"], ["a1", "b1"]]

// try to mutate after assignment - Not able to
var l1Ref = list[0]
print(l1Ref)
>> ["x0", "a0", "b0"]
l1Ref.removeFirst()
print(l1Ref)
>> ["a0", "b0"]
print(list)
// still the same as was before 
>> [["x0", "a0", "b0"], ["a1", "b1"]]

如何在不使用點語法的情況下迭代更改嵌套結構？

Answer 1

數組是Swift中的結構，當您將子數組分配給變量時，會得到該子數組的副本。 要獲得對子數組的引用，請將數組的類型定義為NSMutableArrays的數組：

var array: [NSMutableArray] = [["a", "b", "c"]]
var subArray = array[0]
subArray.removeObjectAtIndex(1)

print(array, subArray)
>> [(a, c)] [(a, c)]

您可以在此處閱讀有關Swift中數組的更多信息