xcode 有人可以发布完整的 NSNumber 用法示例吗？
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Can someone post a full example usage of NSNumber?
提问by Neo42
I'm not even sure, for example, if I can use it like a normal variable. There doesn't appear to be a mutable version. And does mutable mean it's value can be changed?
例如，我什至不确定我是否可以像普通变量一样使用它。似乎没有可变版本。mutable 是否意味着它的值可以改变？
回答by Shaggy Frog
What do you mean by "full example usage"? Can you give a context for the kind of example you're looking for?
“完整示例用法”是什么意思？你能给出你正在寻找的那种例子的背景吗？
What do you mean by using something as a "normal" variable?
使用某些东西作为“正常”变量是什么意思？
You can get an NSNumbereither by using the numberWithXXXfunctions, which returns an autoreleased object, or by doing the standard alloc/init:
您可以NSNumber通过使用numberWithXXX返回自动释放对象的函数或通过执行标准alloc/ 来获得init：
NSNumber* myAllocedNumber = [[NSNumber alloc] initWithFloat:0.0f];
// ...use it...
[myAllocedNumber release];
NSNumber* myAutoreleasedNumber = [NSNumber numberWithFloat:0.0f];
You can later change where your pointer is pointing to, but you can't change the value:
您可以稍后更改指针指向的位置，但不能更改值：
NSNumber* myAutoreleasedNumber = nil;
myAutoreleasedNumber = [NSNumber numberWithFloat:0.0f];
// ...use it...
myAutoreleasedNumber = [NSNumber numberWithInt:1000];
回答by ennuikiller
You can always assign to an immutable variable a different object reference so this works:
你总是可以为一个不可变变量分配一个不同的对象引用，这样就可以了：
NSNumber *intKey;
NSMutableArray *backToString =[[NSMutableArray alloc] init];
while ((intKey = [enumerator nextObject])) {
//(NSNumber *)integer = [key integerValue];
[backToString addObject:[intKey stringValue]];
// code that uses the returned key
}
