iOS 金钱货币的计算问题

发表于

ios开发中涉及到和货币价格计算相关的，都需要注意计算精度的问题。
服务器有可能返回的金钱是int float double string NSNumber, 单纯的float、double的计算都会出现精度问题，即使只是两位小数，也会出现误差。
苹果为我们提供了NSDecimalNumber的API来处理金钱的计算的问题：
​ 1、字符串转float等不精确问题。
​ 2、精确计算
​ 3、保留小数位数
​ 4、四舍五入及其它的保留小数位数规则

直接上代码(已封装)

.h

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#import <Foundation/Foundation.h>
//  金额计算方式
typedef enum {
    Adding,
    Subtracting,
    Multiplying,
    Dividing,
}calucateWay;
@interface DecimalCalucateTool : NSObject
+ (NSString *)decimalNumberCalucate:(NSString *)originValue1 originValue2:(NSString *)originValue2 calucateWay:(calucateWay)calucateWay;
@end

.m

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#import "DecimalCalucateTool.h"
@implementation DecimalCalucateTool
#pragma mark 货币计算
+ (NSString *)decimalNumberCalucate:(NSString *)originValue1 originValue2:(NSString *)originValue2 calucateWay:(calucateWay)calucateWay
{
    NSDecimalNumber *decimalNumber1 = [NSDecimalNumber decimalNumberWithString:originValue1];
    NSDecimalNumber *decimalNumber2 = [NSDecimalNumber decimalNumberWithString:originValue2];
    NSDecimalNumber *product;
    switch (calucateWay) {
        case Adding:
            NSLog(@"+++++++++");
            product = [decimalNumber1 decimalNumberByAdding:decimalNumber2];
            break;
            
        case Subtracting:
            NSLog(@"---------");
            product = [decimalNumber1 decimalNumberBySubtracting:decimalNumber2];
            break;
            
        case Multiplying:
            NSLog(@"*********");
            product = [decimalNumber1 decimalNumberByMultiplyingBy:decimalNumber2];
            break;
            
        case Dividing:
            NSLog(@"/////////");
            product = [decimalNumber1 decimalNumberByDividingBy:decimalNumber2];
            break;
            
        default:
            break;
    }
    return [product stringValue];
}
@end