Question

I want to keep NSUInteger into my core data and I don t know which type should I use (integer 16, 32, 64) to suit the space needed.

From my understanding:

Integer 16 can have minimum value of -32,768 to 32,767
Integer 32 can have minimum value of -2,147,483,648 to 2,147,483,647
Integer 64 can have minimum value of -very large to very large

and NSUInteger is type def of unsigned long which equal to unsigned int (Types in objective-c on iPhone)

...... 如果我把我的NSUInteger改为NSNumber,编号With UnsignInteger:并把它作为NSNumber(Integer 32) 我可以安全检索我的数据?

Answer 1

really 是否需要整个<代码>NSUInteger? 在SOS,这一数值为32比值,可能非常大。它将找到一份已签署的64条轨道。

但是,你可能不需要如此精确。 <代码>uint32_t ,即4 294 967 295 (40亿美元)。如果你第二次加薪一次,就将超过136年的时间达到这一价值。页: 1

Answer 2

If at all possible, when writing data to disk or across a network, it s best to be explicit about the size of value. Instead of using NSUInteger as the datatype, use uint16_t, uint32_t, or uint64_t depending on the range you need. This then naturally translates to Integer 16, 32, and 64 in Core Data.

理解为什么考虑这一设想:

You opt to use Integer 64 type to store your value.
On a 64-bit iOS device (eg iPhone 6) it stores the value 5,000,000,000.
On a 32-bit iOS device this value is fetched from the store into an NSUInteger (using NSNumber s unsignedIntegerValue).

现在,由于NSUInteger在32个轨道装置上仅限32个轨道,因此该数字已不超过5 000 000 000 000 000 000 000 000美元,因为只有一定比例的限额才能达到50亿。如果您在步骤3中转换了NUInteger,uint64_t。这样,价值仍将是50亿美元。

如果你绝对必须使用NSUInteger,那么你就有理由对上文所述问题持怀疑态度,并为之提供防御。

在将未签字的数值储存到似乎已签署的核心数据类型方面,你可以安全储存这些数值并检索:

NSManagedObject *object = // create object
object.valueNumber = @(4000000000); // Store 4 billion in an Integer 32 Core Data type
[managedObjectContext save:NULL] // Save value to store

// Later on
NSManagedObject *object = // fetch object from store
uint32_t value = object.valueNumber.unsignedIntegerValue; // value will be 4 billion

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