在iOS Core Data中存储高精度纬度/经度数 [英] Storing high precision latitude/longitude numbers in iOS Core Data

问题描述

我正在尝试将纬度/经度存储在核心数据中。这些最终会达到6-20位精度。

I'm trying to store Latitude/Longitudes in core data. These end up being anywhere from 6-20 digit precision.

无论出于何种原因，我将它们作为Core Data中的浮点数，它将它们四舍五入并且没有给我准确的价值回来了。我试过十进制类型，也没有运气。

And for whatever reason, i had them as floats in Core Data, its rounding them and not giving me the exact values back. I tried "decimal" type, with no luck either.

NSStrings是我唯一的另一种选择吗？

Are NSStrings my only other option?

编辑

NSManagedObject：

NSManagedObject:

@interface Event :  NSManagedObject  
{
}

@property (nonatomic, retain) NSDecimalNumber * dec;
@property (nonatomic, retain) NSDate * timeStamp;
@property (nonatomic, retain) NSNumber * flo;
@property (nonatomic, retain) NSNumber * doub;

以下是我存储到核心数据中的样本编号的代码：

Here's the code for a sample number that I store into core data:

NSNumber *n = [NSDecimalNumber decimalNumberWithString:@"-97.12345678901234567890123456789"];

打印上述值。甜，值I预期：

The above value printed. Sweet, value I expected:

Printing description of n:

-97.12345678901234567890123456789

再次访问它的代码：

NSNumber *n = [managedObject valueForKey:@"dec"];
NSNumber *f = [managedObject valueForKey:@"flo"];
NSNumber *d = [managedObject valueForKey:@"doub"];

印刷值：

Printing description of n:
    -97.1234567890124

    Printing description of f:
    <CFNumber 0x603f250 [0xfef3e0]>{value = -97.12345678901235146441, type = kCFNumberFloat64Type}

    Printing description of d:
    <CFNumber 0x6040310 [0xfef3e0]>{value = -97.12345678901235146441, type = kCFNumberFloat64Type}

推荐答案

您是否使用过NSNumber包装器？

Have you used the NSNumber wrapper?

将商店配置为使用NSNumber而不是float或decimal，并使用它来保存坐标：

Configure your store to use NSNumber, instead of float or decimal, and use this to save the coordinates:

[NSNumber numberWithDouble:coordinate.latitude]
//Same for longitude.

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