blocks|key|5446954|text|返回包装在NSNumber中的float，然后就可以使用id返回类型了。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|5446955|为了简化它，您甚至可以使用装箱文字，例如：|5446956|return+@(1.1f);|code-block|syntax|javascript|5446957|entityMap^0|5|8|F|5|S|2|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]|$9|R|A|S|B|C]|$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|V|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|W|8|@]|D|@]|E|$K|L]]|$1|M|3|-4|5|6|7|X|8|@]|D|@]|E|$]]]|N|$]]

Return a <code>float</code> wrapped in an <code>NSNumber</code>, then you can use the <code>id</code> return type.

To simplify it, you can even use boxing literals, for example:

<pre><code>return @(1.1f);
</code></pre>

blocks|key|1662203|text|首先要考虑的是，为什么需要一个可以返回任何类型的函数。这真的没有意义，因为你不知道类型，所以你不能给任何东西赋值。当然，当严格处理Obj-C对象时，情况会有所不同，因为该语言使用带有id关键字的未知对象。未知物体就像是把蜜糖苹果和麦金塔苹果混在一起(没有双关语)，而你想做的就像把蜜糖苹果和飞机混在一起！但是，如果您希望根据参数返回某个类型(例如，为int参数返回int，为float参数返回float+)，则可以重载这些函数。否则，我所知道的唯一返回任何东西的方法就是一个空指针(void+*)。这将指向一大块数据，实际上可以是任何东西。但回到最初的问题。它代表什么?它有多长时间？祝好运!|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1662204|更新:正如其他答案所提到的，您可以包装简单的数据类型(int、float等)。在诸如NSNumbers或NSValues之类的对象中，这将适用于您的情况。但是，当扩展到具有复杂类型(如结构)的更一般的场景时，这些通常不能包装在内置类中。您需要使用Obj-C创建自己的类。|1662205|entityMap^0|2J|2|4V|3|52|3|57|5|5G|5|6P|6|0|R|3|V|5|0^^$0|@$1|2|3|4|5|6|7|J|8|@$9|K|A|L|B|C]|$9|M|A|N|B|C]|$9|O|A|P|B|C]|$9|Q|A|R|B|C]|$9|S|A|T|B|C]|$9|U|A|V|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|W|8|@$9|X|A|Y|B|C]|$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|H|3|-4|5|6|7|11|8|@]|D|@]|E|$]]]|I|$]]

The first thing to think about is why you would need a function that can return any type. It really doesn't make sense because you wouldn't be able to assign the value to anything, since you don't know the type. Of course, the situation is different when dealing strictly with Obj-C objects, as the language utilizes unknown objects with the <code>id</code> keyword. Unknown objects are like mixing Honeycrisp apples with Macintosh apples (no pun intended), and what you are trying to do is like mixing Honeycrisp apples with airplanes! However, if you want a certain type returned based off of the parameters (such as returning <code>int</code> for <code>int</code> parameters and <code>float</code> for <code>float</code> parameters), then you can overload the functions. Otherwise, then only way that I know of to return absolutely anything would be a void pointer (<code>void *</code>). This would point to a chunk of data that could really be anything. But back to the original problem. What does it represent and how long is it? Good luck!

UPDATE: As other answers mention, you can wrap simple data types (<code>int</code>, <code>float</code>, etc.) in objects such as NSNumbers or NSValues, which will work for your case. But when extending to more general scenarios with complex types such as structs, these generally can't be wrapped in built-in classes. You would need to make your own class using Obj-C.

blocks|key|1433202|text|Obj-C中没有这种多态性。如果你事先知道会返回什么，那么你当然可以使用to方法。当您使用NSNumber作为浮点值时，缩减id将会起作用。您甚至可以引入一个包含数字或字符串的响应对象，并为以后的处理提供(bool)+isNumber和(bool)+isString方法。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1433203|但你到底想做什么？你在什么背景下使用它，你真正想要实现的是什么。在我看来，似乎有更好的解决方案。|1433204|entityMap^0|2U|F|3A|F|0|0^^$0|@$1|2|3|4|5|6|7|J|8|@$9|K|A|L|B|C]|$9|M|A|N|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|O|8|@]|D|@]|E|$]]|$1|H|3|-4|5|6|7|P|8|@]|D|@]|E|$]]]|I|$]]

There is no polymorphism of that kind in Obj-C. 
If you know in advance what will be returned then you could use to methods of course. 
Retruning id would work when you use an NSNumber for the float value. 
You could even introduce a response object that either carries a number or a string and provides <code>(bool) isNumber</code> and <code>(bool) isString</code> methods for later processing. 

But what are you really up to? In which context are you using that and what do you really try to achieve. To me it sounds as if there may be better solutions available.

blocks|key|1433210|text|当然，这是一个奇怪的解决方案，但是你有一个奇怪的问题。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1433211|您需要启用objective-c%2B%2B：将.m-file重命名为.mm，然后您的代码将如下所示：|1433212|void+weird_function(int+a)
{
+++switch+(a)
+++{
+++++++case+0:+throw+@"Hello";
+++++++default:+throw+a;
+++}
}

void+some_code(int+a)
{
++++try
++++{
++++++++weird_function(a);
++++}
++++catch+(int+a)
++++{
+++++++++NSLog(@"Catch+int:+%25d",+a);
++++}
++++catch+(NSString*+str)
++++{
+++++++++NSLog(@"Catch+string:+%25@",+str);
++++}
}|code-block|syntax|javascript|1433213|你的方法可以像这样实现：|1433214|union+ValueHolder
{
++++void*+voidPtrValue;
++++int+intValue;
++++float+floatValue;
++++NSString*+nssstringValue;
};

-+(void)getIvarWithName:(const+char+*)name+in:(id)obj
{
++++ValueHolder+vh;
++++Ivar+ivar+=+object_getInstanceVariable(obj,name,+&vh.voidPtrValue));
++++if+(NULL+==+ivar)
++++++++return;
++++const+char*+encoding+=+ivar_getTypeEncoding(ivar);
++++if+(0+==+strcmp(encoding,+@encode(int)))
++++++++throw+vh.intValue;
++++if+(0+==+strcmp(encoding,+@encode(float)))
++++++++throw+vh.floatValue;
++++if+(0+==+strcmp(encoding,+"@\"NSString\""))
++++++++throw+vh.nsstringValue;
}|1433215|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Q|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|R|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

Ofcourse it's weird solution, but you have weird question.

You need enable objective-c++: rename .m-file to .mm
Then yours code will look something like that:

<pre><code>void weird_function(int a)
{
 switch (a)
 {
 case 0: throw @"Hello";
 default: throw a;
 }
}

void some_code(int a)
{
 try
 {
 weird_function(a);
 }
 catch (int a)
 {
 NSLog(@"Catch int: %d", a);
 }
 catch (NSString* str)
 {
 NSLog(@"Catch string: %@", str);
 }
}
</code></pre>

Yours method can be implemented something like that:

<pre><code>union ValueHolder
{
 void* voidPtrValue;
 int intValue;
 float floatValue;
 NSString* nssstringValue;
};

- (void)getIvarWithName:(const char *)name in:(id)obj
{
 ValueHolder vh;
 Ivar ivar = object_getInstanceVariable(obj,name, &amp;vh.voidPtrValue));
 if (NULL == ivar)
 return;
 const char* encoding = ivar_getTypeEncoding(ivar);
 if (0 == strcmp(encoding, @encode(int)))
 throw vh.intValue;
 if (0 == strcmp(encoding, @encode(float)))
 throw vh.floatValue;
 if (0 == strcmp(encoding, "@\"NSString\""))
 throw vh.nsstringValue;
}
</code></pre>

blocks|key|1427976|text|我发现在c%2B%2B中使用模板来创建自定义类型是可行的，下面的代码最适合我的情况：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1427977|template+<typename+_type>
static+inline+_type+&+hookVar(id+self,+NSString*name)
{
++++Ivar+ivar(class_getInstanceVariable(object_getClass(self),[name+UTF8String]));
++++#if+__has_feature(objc_arc)
++++void+*pointer(ivar+==+NULL+?+NULL+:+reinterpret_cast<char+*>((__bridge+void+*)self)+%2B+ivar_getOffset(ivar));
++++#else
++++void+*pointer(ivar+==+NULL+?+NULL+:+reinterpret_cast<char+*>(self)+%2B+ivar_getOffset(ivar));
++++#endif
++++return+*reinterpret_cast<_type+*>(pointer);
}|code-block|syntax|javascript|1427978|要调用该函数，我只需使用如下代码：|1427979|NSWindow+*win+=+hookVar<NSWindow*>(self,+@"_window");|1427980|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

I found that using a template in c++ works to have a custom type
The following code works best for my situation:

<pre><code>template &lt;typename _type&gt;
static inline _type &amp; hookVar(id self, NSString*name)
{
 Ivar ivar(class_getInstanceVariable(object_getClass(self),[name UTF8String]));
 #if __has_feature(objc_arc)
 void *pointer(ivar == NULL ? NULL : reinterpret_cast&lt;char *&gt;((__bridge void *)self) + ivar_getOffset(ivar));
 #else
 void *pointer(ivar == NULL ? NULL : reinterpret_cast&lt;char *&gt;(self) + ivar_getOffset(ivar));
 #endif
 return *reinterpret_cast&lt;_type *&gt;(pointer);
}
</code></pre>

To call the function I just use something like:

<pre><code>NSWindow *win = hookVar&lt;NSWindow*&gt;(self, @"_window");
</code></pre>

How can I have a method/function that can return any type? For example sometimes the type will need to be <code>float</code> and sometimes it will need to be <code>NSString*</code> so <code>id</code> won't work because <code>float</code> isn't an <code>id</code>. I am not opposed to doing it in a c or c++ function if it's easier.

The reason why I need a dynamic return type is because I'm using objc/runtime to get an Ivar. 

I would like some_type to be able to anything:

<pre><code>- (some_type)getIvarWithName:(const char *)name in:(id)obj
{
Ivar ivar(class_getInstanceVariable(object_getClass(obj),name));
return (some_type)ivar;
}
</code></pre>

Varying Return Type Objective-C or c

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我怎么能有一个可以返回任何类型的方法/函数呢？例如，有时类型需要是float，有时需要是NSString*，这样id就不能工作了，因为float不是id。我不反对在c或c++函数中这样做，如果这样更容易的话。我需要动态返回类型的原因是因为我使用objc/ get来获取Ivar。我希望some_type能够做任何事情：-...

问可变回报类型Objective-C或C
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