修改字典的数组里面字典财产。错误：无法分配给类型的不可变的前pression [字符串：AnyObject] [英] Modifying dictionary property inside of array of dictionaries. Error: Cannot assign to immutable expression of type [String:AnyObject]

问题描述

有对SO <一个几个职位href=\"http://stackoverflow.com/questions/24721555/how-does-one-create-a-mutable-copy-of-an-immutable-array-in-swift\">like这，而唯一的解决方案建议，似乎工作手动删除和相同的索引中插入一个属性。

There are several posts on SO like this, and the only solution suggested that would seem to work is manually removing and inserting a property at the same index.

不过，这感觉凌乱，有的帖子建议它在X code 7可以直接更新字典的属性，如果字典的数组里面。

But this feels messy, and some posts suggest it's possible in Xcode 7 to directly update dictionary properties if inside an array of dictionaries.

但是，它不工作为code以下时，产生的无法分配给一成不变EX型$ P ​​$ pssion [字符串：AnyObject]。误差

However, it's not working for the code below, generating the Cannot assign to immutable expression of type [String:AnyObject] error.

// Class vars
var userDict = [String:AnyObject]()
var accounts = [[String:AnyObject]]()

func setHistory(index: Int, history: [String]) {
    (userDict["accounts"] as! [[String:AnyObject]])[index]["history"]! = history
    (userDict["accounts"] as! [[String:AnyObject]])[index]["history"] = history
    userDict["accounts"][index]["history"] = history
    userDict["accounts"][index]["history"]! = history
}

setHistory 内尝试做同样的事情，所有的失败。所有的四行

All four lines inside of setHistory try to do the same thing, and all fail.

推荐答案

现在的方式，你这样做是：
的UserDict [账户]作为！ [字符串：AnyObject]]）[指数] [历史]
您正在使用一个不可变对象的工作。

Right now the way you are doing this: userDict["accounts"] as! [[String:AnyObject]])[index]["history"] you are working with an immutable container.

您将不得不设计出这样的：

You are going to have to design it like this:

func setHistory(index: Int, history: [String]) {
    //this line copies from user dict,  it is not a pointer
    var account = userDict["accounts"] as! [[String:AnyObject]];
    //this line sets the new history
    account[index]["history"] = history;
    //this line will update the dictionary with the new data
    userDict["accounts"] = account


}

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