NSJSONSerialization取消开箱NSNumber吗? [英] NSJSONSerialization unboxes NSNumber?

问题描述

我正在使用NSJSONSerialization将JSON文档转换为Core Foundation类型.

I'm using NSJSONSerialization to turn a JSON document into the Core Foundation types.

我的JSON中有一个字段是数字".有时是整数，有时是浮点数.

I have a field in my JSON which is a "number". It's sometimes and integer, sometimes a float.

现在，问题是当NSJSONSerialization将我的JSON转换为NSDictionary时，我尝试使用objectForKey提取数字，有时是int，有时是double.似乎NSJSONSerialization并不只是将其保留在NSNumber包装器中，而是实际上将值拆箱，然后将 that 插入到NSDictionary中.

Now, the problem is when NSJSONSerialization turns my JSON into an NSDictionary and I try to extract the number using objectForKey, sometimes it's an int, and sometimes it's a double. It seems NSJSONSerialization doesn't simply leave it in an NSNumber wrapper, but actually unboxes the value, and inserts that into the NSDictionary.

很奇怪.我以为您应该将基元放入NSDictionary中.因此，我现在的问题是我不知道应该使用哪种类型(整数或双精度)来保留实际的数字值.

Very strange. I thought you we're supposed to put primitives into an NSDictionary. So the problem I have now is that I don't know what type (int or double) I should be casting to to preserve the actual number value.

有人知道出路吗?

推荐答案

您可以从NSNumber获取原始类型.只需使用以下代码段即可:

You can get primitive type from NSNumber. Just use following code snippet:

    const char* type = [theValue objCType];
if (strcmp (type, @encode (NSInteger)) == 0) {
    //It is NSInteger
} else if (strcmp (type, @encode (NSUInteger)) == 0) {
    //It is NSInteger
} else if (strcmp (type, @encode (int)) == 0) {
    //It is NSUInteger
} else if (strcmp (type, @encode (float)) == 0) {
    //It is float
} else if (strcmp (type, @encode (double)) == 0) {
    //It is double
} else if (strcmp (type, @encode (long)) == 0) {
    //It is long
} else if (strcmp (type, @encode (long long)) == 0) {
    //It is long long
}

等等.

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