iOS NSNumber 加、减、乘、除

NSNumber 加、减、乘、除 包括 根据需求转换字符串（四舍五入、货币数字、百分比。。。。）

开发中会遇到一些字符串显示看似乱码的情况 比如 2.7E9292
或者说显示的数字和后台的对不上 比如后端返回2.938 前端显示2.938888888
解决方法

#import 

NS_ASSUME_NONNULL_BEGIN
typedef NS_ENUM(NSUInteger, YQOPERATORS){
    YQ_Add,//加
    YQ_Mul,//乘
    YQ_Sub,//减
    YQ_Div//除
};
@interface NSNumber (YQ)

//无格式,四舍五入
- (NSString *)changeToumberFormatterNoStyle;
//小数型,
- (NSString *)changeToNumberFormatterDecimalStyle;
//货币型,
- (NSString *)changeToNumberFormatterCurrencyStyle;
//百分比型
- (NSString *)changeToNumberFormatterPercentStyle;
//科学计数型,
- (NSString *)changeToNumberFormatterScientificStyle;
//全拼
- (NSString *)changeToNumberFormatterSpellOutStyle;


/// 运算方法
/// @param one 第一个数
/// @param opera 运算方式
/// @param two 第二个数
+ (NSNumber *)getResult:(NSNumber *)one  operators:(YQOPERATORS)opera num:(NSNumber *)two;

@end

NS_ASSUME_NONNULL_END

//
//  NSNumber+YQ.m
//  yaqu
//
//  Created by 刘浩宇 on 2020/11/19.
//  Copyright © 2020 nalovy. All rights reserved.
//

#import "NSNumber+YQ.h"

@implementation NSNumber (YQ)

//
//    NSNumberFormatterNoStyle = kCFNumberFormatterNoStyle, //无格式,四舍五入，原值2.7999999999,直接输出3
//    NSNumberFormatterDecimalStyle = kCFNumberFormatterDecimalStyle, //小数型,保留小数输出2.8
//    NSNumberFormatterCurrencyStyle = kCFNumberFormatterCurrencyStyle, //货币型,加上了人民币标志，原值输出￥2.8
//    NSNumberFormatter
//    NSNumberFormatterPercentStyle = kCFNumberFormatterPercentStyle,  //百分比型,本身数值乘以100后用百分号表示,输出280%
//    NSNumberFormatterScientificStyle = kCFNumberFormatterScientificStyle, //科学计数型,原值表示，输出2.799999999E0
//    NSNumberFormatterSpellOutStyle = kCFNumberFormatterSpellOutStyle  //全拼,原值的中文表示，输出二点七九九九...
- (NSString *)changeStyle:(NSNumberFormatterStyle)style {
    NSNumberFormatter *formatter = [[NSNumberFormatter alloc] init];
    formatter.numberStyle = style;
    return [formatter stringFromNumber:self];
}

- (NSString *)changeToumberFormatterNoStyle {
    return [self changeStyle:NSNumberFormatterNoStyle];
}

- (NSString *)changeToNumberFormatterDecimalStyle {
    return [self changeStyle:NSNumberFormatterDecimalStyle];
}

- (NSString *)changeToNumberFormatterCurrencyStyle {
    return [self changeStyle:NSNumberFormatterCurrencyStyle];
}

- (NSString *)changeToNumberFormatterPercentStyle {
    return [self changeStyle:NSNumberFormatterPercentStyle];
}

- (NSString *)changeToNumberFormatterScientificStyle {
    return [self changeStyle:NSNumberFormatterScientificStyle];
}

- (NSString *)changeToNumberFormatterSpellOutStyle {
    return [self changeStyle:NSNumberFormatterSpellOutStyle];
}

+ (NSNumber *)getResult:(NSNumber *)one operators:(YQOPERATORS)opera num:(NSNumber *)two {
    NSDecimalNumber *resultNum = [[NSDecimalNumber alloc] init];
    NSDecimalNumber *A = [NSDecimalNumber decimalNumberWithDecimal:one.decimalValue];
    NSDecimalNumber *B = [NSDecimalNumber decimalNumberWithDecimal:two.decimalValue];
    NSDecimalNumberHandler *roundingBehavior = [NSDecimalNumberHandler decimalNumberHandlerWithRoundingMode:NSRoundPlain
                                                           scale:2
                                                raiseOnExactness:NO
                                                 raiseOnOverflow:NO
                                                raiseOnUnderflow:NO
                                             raiseOnDivideByZero:NO];

    if (opera == YQ_Add) {
        resultNum = [A decimalNumberByAdding:B withBehavior:roundingBehavior];
    }else if (opera == YQ_Sub) {
        // 减法
        resultNum = [A decimalNumberBySubtracting:B withBehavior:roundingBehavior];
    }else if (opera == YQ_Mul) {
        resultNum = [A decimalNumberByMultiplyingBy:B withBehavior:roundingBehavior];
    }else if (opera == YQ_Div) {
        // 除法
        resultNum = [A decimalNumberByDividingBy:B withBehavior:roundingBehavior];
    }
    return resultNum;
}


@end