OC : NSDecimalNumber

NSDecimalNumber : NSNumber

NSDecimalNumber-十进制数，继承于NSNumber。
可以有小数点，可以是正负数。

初始化

【1】

+ (NSDecimalNumber *)decimalNumberWithMantissa:(unsigned long long)mantissa exponent:(short)exponent isNegative:(BOOL)flag;

mantissa：长整形；exponent：指数；flag：正负数。

//12.75NSDecimalNumber *subtotalAmount = [NSDecimalNumber decimalNumberWithMantissa:1275 exponent:-2 isNegative:NO];   //-127500NSDecimalNumber  subtotalAmountTwo = [NSDecimalNumber decimalNumberWithMantissa:1275 exponent:2 isNegative:YES];   

【2】

+ (NSDecimalNumber *)decimalNumberWithDecimal:(NSDecimal)dcm;

将C语言NSDecimal类型转成一个十进制数。

//12.75NSDecimalNumber *subtotalAmount = [NSDecimalNumber decimalNumberWithMantissa:1275 exponent:-2 isNegative:NO];   NSDecimal decimalValue = [subtotalAmount decimalValue];  /*    数据结构：   (NSDecimal) decimalValue = {   _exponent = -2   _length = 1   _isNegative = 0   _isCompact = 1   _reserved = 0   _mantissa = ([0] = 1275, [1] = 0, [2] = 0, [3] = 0, [4] = 0, [5] = 0, [6] = 0, [7] = 0)   }   */  subtotalAmount = [NSDecimalNumber decimalNumberWithDecimal:decimalValue];   //12.75

如果您只想从float或int常量中获取NSDecimalNumber，请尝试以下操作：

NSDecimalNumber *dn = [NSDecimalNumber decimalNumberWithDecimal:[NSNumber numberWithFloat:2.75f] decimalValue];

【3】

+ (NSDecimalNumber *)decimalNumberWithString:(nullable NSString *)numberValue;

//将字符串转成一个十进制数。

NSDecimalNumber *discountAmount = [NSDecimalNumber decimalNumberWithString:@"-12.74"];      //-12.74  discountAmount = [NSDecimalNumber decimalNumberWithString:@"127.4"];      //127.4

【4】
+ (NSDecimalNumber *)decimalNumberWithString:(nullable NSString *)numberValue locale:(nullable id)locale;

这个有点复杂，locale代表一种格式，就像date的格式化一样。这里的locale可以传递两种格式NSDictionary类型：

NSDictionary *locale = [NSDictionary dictionaryWithObject:@"," forKey:NSLocaleDecimalSeparator];    //以","当做小数点格式NSDecimalNumber *discountAmount = [NSDecimalNumber decimalNumberWithString:@"123,40" locale:locale];    //123.4

NSLocale *locale = [[NSLocale alloc] initWithLocaleIdentifier:@"fr_FR"];    //法国数据格式,法国的小数点是','逗号NSDecimalNumber *discountAmount = [NSDecimalNumber decimalNumberWithString:@"123,40" locale:locale];    //123.4

Property

+(NSDecimalNumber *)zero; //0+(NSDecimalNumber *)one; //1+(NSDecimalNumber *)minimumDecimalNumber;//-3402823669209384634633746074317682114550000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000+(NSDecimalNumber *)maximumDecimalNumber;//3402823669209384634633746074317682114550000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000+(NSDecimalNumber *)notANumber;//非数字，常用于对比，比如：//[[NSDecimalNumber notANumber] isEqualToNumber:myNumber];

运算

加

-(NSDecimalNumber *)decimalNumberByAdding:(NSDecimalNumber *)decimalNumber;

-(NSDecimalNumber *)decimalNumberByAdding:(NSDecimalNumber *)decimalNumber withBehavior:(nullable id <NSDecimalNumberBehaviors>)behavior;

减

-(NSDecimalNumber *)decimalNumberBySubtracting:(NSDecimalNumber *)decimalNumber;

-(NSDecimalNumber *)decimalNumberBySubtracting:(NSDecimalNumber *)decimalNumber withBehavior:(nullable id <NSDecimalNumberBehaviors>)behavior;

乘

-(NSDecimalNumber *)decimalNumberByMultiplyingBy:(NSDecimalNumber *)decimalNumber;

-(NSDecimalNumber *)decimalNumberByMultiplyingBy:(NSDecimalNumber *)decimalNumber withBehavior:(nullable id <NSDecimalNumberBehaviors>)behavior;

除

-(NSDecimalNumber *)decimalNumberByDividingBy:(NSDecimalNumber *)decimalNumber;

-(NSDecimalNumber *)decimalNumberByDividingBy:(NSDecimalNumber *)decimalNumber withBehavior:(nullable id <NSDecimalNumberBehaviors>)behavior;

a的n次方

-(NSDecimalNumber *)decimalNumberByRaisingToPower:(NSUInteger)power;

-(NSDecimalNumber *)decimalNumberByRaisingToPower:(NSUInteger)power withBehavior:(nullable id <NSDecimalNumberBehaviors>)behavior;

指数运算

-(NSDecimalNumber *)decimalNumberByMultiplyingByPowerOf10:(short)power;

-(NSDecimalNumber *)decimalNumberByMultiplyingByPowerOf10:(short)power
withBehavior:(nullable id <NSDecimalNumberBehaviors>)behavior;

四舍五入运算

-(NSDecimalNumber *)decimalNumberByRoundingAccordingToBehavior:(nullable id <NSDecimalNumberBehaviors>)behavior;

比较运算

-(NSComparisonResult)compare:(NSNumber *)decimalNumber;

NSDecimalNumber *discount1 = [NSDecimalNumber decimalNumberWithString:@"1.2"];  NSDecimalNumber *discount2 = [NSDecimalNumber decimalNumberWithString:@"1.3"];  NSComparisonResult result = [discount1 compare:discount2];  if (result == NSOrderedAscending) {      NSLog(@"1.2 < 1.3");  } else if (result == NSOrderedSame) {      NSLog(@"1.2 == 1.3");  } else if (result == NSOrderedDescending) {      NSLog(@"1.2 > 1.3");  }

推荐阅读

如何使用NSDecimalNumber？
https://gxnotes.com/article/101442.html

‘NSDecimalNumber–十进制数’使用方法
http://www.jianshu.com/p/4703d704c953