How can I downcast array of AnyObject arrays to array of String arrays?
如何将AnyObject数组的数组转换为String数组的数组？
i tried the following code:
我尝试了以下代码：
let v1:[[AnyObject]] = [["hello"]] // v1 type is [[AnyObject]]
let v2 = v1 as! [[String]] // compile error!
but this code will not compile with an error:
但是这段代码不会编译出错：
'String' is not identical to 'AnyObject'
'String'与'AnyObject'不同
if I just try to downcast array of AnyObject to array of String, it works fine:
如果我只是尝试将AnyObject的数组向下转换为String数组，它可以正常工作：
let v1:[AnyObject] = ["hello"] // v1 type is [AnyObject]
let v2 = v1 as! [String] // v2 type is [String] as expected
1 个解决方案
#1
9
You've already answered your own question. Do in the first code, to each element of the array, what you're successfully doing in the second code. Like this:
你已经回答了自己的问题。在第一个代码中，对数组的每个元素，在第二个代码中成功执行的操作。喜欢这个：
let v2 = v1.map {$0 as! [String]}
#1
9
You've already answered your own question. Do in the first code, to each element of the array, what you're successfully doing in the second code. Like this:
你已经回答了自己的问题。在第一个代码中，对数组的每个元素，在第二个代码中成功执行的操作。喜欢这个：
let v2 = v1.map {$0 as! [String]}