ios “使用'NSNumber *'类型的表达式初始化'int'的整数转换指针不兼容”

"Incompatible pointer to integer conversion initializing 'int' with an expression of type 'NSNumber *'"

提问by Phil

I suspect this is something really simple, but I'm trying to get an int that I have stored in a dictionary and the line I'm using is this..

我怀疑这真的很简单，但我试图获得一个我存储在字典中的 int，我正在使用的行是这个..

 int mapX = [NSNumber numberWithInt:[templateObject valueForKey:@"mapX"]];

But it's giving me the error...

但它给了我错误...

Incompatible pointer to integer conversion sending 'id' to parameter of type 'int'

不兼容的整数转换指针将“id”发送到“int”类型的参数

and

和

Incompatible pointer to integer conversion initializing 'int' with an expression of type 'NSNumber *';

指向整数转换的不兼容指针，使用类型为“NSNumber *”的表达式初始化“int”；

If I try...

如果我尝试...

NSNumber *mapX = [NSNumber numberWithInt:[templateObject valueForKey:@"mapX"]];

I basically get the same error. I know I'm probably just using the wrong syntax, but I'm not sure how else to write it.

我基本上得到了同样的错误。我知道我可能只是使用了错误的语法，但我不确定如何编写它。

Thanks for any help.

谢谢你的帮助。

回答by WDUK

A couple of points:

几点：

• [NSNumber numberWithInt:[templateObject valueForKey:@"mapX"]];

  Returns an NSNumber*, which you're trying to store in an int.

• NSNumber* mapX = [NSNumber numberWithInt:[templateObject valueForKey:@"mapX"]];

  won't work either, because [templateObject valueForKey:@"mapX"]isn't an int. You can only store objects in NSDictionary, not primitive types.

• [NSNumber numberWithInt:[templateObject valueForKey:@"mapX"]];

  返回一个NSNumber*，您试图将其存储在 int 中。

• NSNumber* mapX = [NSNumber numberWithInt:[templateObject valueForKey:@"mapX"]];

  也不会工作，因为[templateObject valueForKey:@"mapX"]不是int. 您只能在 中存储对象NSDictionary，而不能在原始类型中存储。

You might want to try (Assuming I have the types correct)

您可能想尝试（假设我的类型正确）

NSNumber* mapXNum = [templateObject valueForKey:@"mapX"];
int mapX = [mapXNum intValue];

回答by jungledev

 int mapX = (int)[[templateObject valueForKey:@"mapX"] integerValue];

the above solution is assuming the templateObject valueForKey:@"mapX" returns an NSNumber. If it doesn't and you want to convert it to an NSNumber, use this solution instead:

上述解决方案假设 templateObject valueForKey:@"mapX" 返回一个 NSNumber。如果不是，并且您想将其转换为 NSNumber，请改用此解决方案：

 int mapX = (int)[(NSNumber *)[templateObject valueForKey:@"mapX"] integerValue];

Typecasting in ObjC is the.worst.

ObjC 中的类型转换是最糟糕的。

回答by jungledev

int mapX = [NSNumber numberWithInt:[templateObject valueForKey:@"mapX"]];

makes no sense for two reasons (think about it for a moment), however

没有意义有两个原因（想一想），但是

NSNumber *mapX = [NSNumber numberWithInt:[[templateObject valueForKey:@"mapX"] intValue]];

should work assuming [templateObject valueForKey:@"mapX"]is either an NSNumberor an NSStringinstance.

应该工作假设[templateObject valueForKey:@"mapX"]是一个NSNumber或一个NSString实例。

回答by Adam Rosenfield

You have two problems. First, [templateObject valueForKey:@"mapX"]returns an id, which is a pointer to an Objective-C object, not an int. And since the -[NSNumber numberWithInt:]method takes an intparameter, trying to convert an idto an intis an error.

你有两个问题。首先，[templateObject valueForKey:@"mapX"]返回 an id，它是一个指向 Objective-C 对象的指针，而不是一个int。由于该-[NSNumber numberWithInt:]方法接受一个int参数，尝试将 an 转换id为 anint是一个错误。

The second problem is that you try to convert the result of [NSNumber numberWithInt:...]to an int, which is again the same problem: -[NSNumber numberWithInt:]returns a pointer to an NSNumberobject, which is not an int.

第二个问题是您尝试将 的结果转换[NSNumber numberWithInt:...]为 an int，这又是同样的问题：-[NSNumber numberWithInt:]返回一个指向NSNumber对象的指针，而不是int。

Assuming that the value stored in your dictionary is in fact an NSNumber, what you really want to do is this:

假设存储在您的字典中的值实际上是 an NSNumber，您真正想要做的是：

NSNumber *mapXObj = [templateObject valueForKey:@"mapX"];  // Implicit cast from id to NSNumber*
int mapX = [mapXObj intValue];

Or more succinctly:

或者更简洁：

int mapX = [[templateObject valueForKey:@"mapX"] intValue];