iOS_金融类浮点数据处理(例：单位转换、添加分隔符、舍弃第三位小数等)

记在前面：其他工具类方法可查看我另一篇文章（我就是传送门）。

金融浮点工具类我就全部都贴出来吧，有多余的方法不需要再自己删除。

DecimalsTool.h

#import 


// 浮点数据精度矫正工具
@interface DecimalsTool : NSObject

#pragma mark - 直接舍弃
/**
 直接舍弃第三位小数,返回值保留两位小数(例: 1.5555>>>1.55)
 */
+ (double)abandonThird:(double)flt;

/**
 保留全部小数，若小数最后一位为0则把0舍弃(例: 1.1111>>>1.1111   1.0000>>>1  )
 */
+ (NSString *)stringAllDecimals:(double)flt;

/**
 若小数最后一位为0则把0舍弃，结果最少保留一位小数(例:1.0100>>>1.01    1.0000>>>1.0)
 */
+ (NSString *)stringLeastOneDecimals:(double)flt;

/**
 若小数最后一位为0则把0舍弃，结果最少保留两位小数(例:1.0100>>>1.01    1.0000>>>1.00)
 */
+ (NSString *)stringLeastTwoDecimals:(double)flt;

/**
 若小数最后一位为0则把0舍弃，结果最多保留两位小数(例:1.1111>>>1.11     1.0000>>>1)
 */
+ (NSString *)stringMostTwoDecimals:(double)flt;


#pragma mark 拓展方法
/**
 加英文逗号分隔符(金额适用),至少保留两位小数(例:1000000000.0000>>>1,000,000,000.00    1000000000.00001>>>1,000,000,000.000001)
 */
+ (NSString *)addSemicolonLestTwoDecimals:(double)flt;

/**
 加英文逗号分隔符(金额适用),保留两位小数(例:1000000000.0000>>>1,000,000,000.00)
 */
+ (NSString *)addSemicolonKeepDecimals:(double)flt;

/**
 加英文逗号分隔符(金额适用),不保留小数(例:1000000000.0000>>>1,000,000,000)
 */
+ (NSString *)addSemicolonNoDecimals:(double)flt;

/**
 添加单位“元”或“万元”(优惠券等福利型场景使用)，保留最后1位不为0的小数，若少于1万最多保留2位小数
 */
+ (NSString *)addUnitWelfareDecimals:(double)flt;
/**
 添加单位“元”或“万”(优惠券等福利型场景使用)，保留最后1位不为0的小数，若少于1万最多保留2位小数
 */
+ (NSString *)addUnitWelfareDecimals2:(double)flt;

/**
 添加单位“万”(通用方法)，至少保留两位小数
 @param subUnit 附加单位（例：subUnit = @"元"，return @"xx元"或@"xx万元"）
 */
+ (NSString *)addUnitCommonDecimals:(double)flt subUnit:(NSString *)subUnit;

/**
 回报率精度处理    至少保留1位小数、小数超过4位，则从第5位四舍五入，最多保留4位
 */
+ (NSString *)rateDecimals:(double)flt;

@end

DecimalsTool.m

#import "DecimalsTool.h"

@implementation DecimalsTool

#pragma mark - 直接舍弃
/**
 直接舍弃第三位小数,返回值保留两位小数(例: 1.5555>>>1.55)
 */
+ (double)abandonThird:(double)flt {
    // 旧方法
//    NSString *ds = [NSString stringWithFormat:@"%.8lf", flt];
//    NSString *cs = [ds substringToIndex:ds.length-6];
//    return [cs doubleValue];
    // 新方法
    return floor(flt*100)/100.0;
}

/**
 保留全部小数，若小数最后一位为0则把0舍弃(例: 1.1111>>>1.1111   1.0000>>>1  )
 */
+ (NSString *)stringAllDecimals:(double)flt {
    NSString *ds = [NSString stringWithFormat:@"%.8lf", flt];
    NSString *cs = [ds substringToIndex:ds.length-2];

    NSArray *array = [cs componentsSeparatedByString:@"."];
    NSString *decimalStr = [array lastObject];
    
    for (NSInteger i = decimalStr.length - 1; i >= 0; i--) {
        NSString *tmpStr = [decimalStr substringWithRange:NSMakeRange(i, 1)];
        if ([tmpStr isEqualToString:@"0"]) {
            if (i==0) {
                decimalStr = @"";
            }else {
                decimalStr = [decimalStr substringToIndex:i];
            }
        }else {
            break;
        }
    }
    if (decimalStr.length>0) {
        return [NSString stringWithFormat:@"%@.%@", [array firstObject], decimalStr];
    }else {
        return [NSString stringWithFormat:@"%@", [array firstObject]];
    }
}

/**
 若小数最后一位为0则把0舍弃，结果最少保留一位小数(例:1.0100>>>1.01    1.0000>>>1.0)
 */
+ (NSString *)stringLeastOneDecimals:(double)flt {
    NSString *ds = [self stringAllDecimals:flt];
    NSArray *array = [ds componentsSeparatedByString:@"."];
    if (array.count > 1) {
        NSString *lastStr = [array lastObject];
        if (lastStr.length > 2) {
            lastStr = [lastStr substringToIndex:2];
        }
        return [NSString stringWithFormat:@"%@.%@", [array firstObject], lastStr];
    }else {
        return [NSString stringWithFormat:@"%@.0", [array firstObject]];
    }
}

/**
 若小数最后一位为0则把0舍弃，结果最少保留两位小数(例:1.0100>>>1.01    1.0000>>>1.00)
 */
+ (NSString *)stringLeastTwoDecimals:(double)flt {
    NSString *ds = [self stringAllDecimals:flt];
    NSArray *array = [ds componentsSeparatedByString:@"."];
    if (array.count > 1) {
        NSString *lastStr = [array lastObject];
        if (lastStr.length == 1) {
            return [NSString stringWithFormat:@"%@.%@0", [array firstObject], lastStr];
        }
        return [NSString stringWithFormat:@"%@.%@", [array firstObject], lastStr];
    }else {
        return [NSString stringWithFormat:@"%@.00", [array firstObject]];
    }
}

/**
 若小数最后一位为0则把0舍弃，结果最多保留两位小数(例:1.1111>>>1.11     1.0000>>>1)
 */
+ (NSString *)stringMostTwoDecimals:(double)flt {
    NSString *ds = [self stringAllDecimals:flt];
    NSArray *array = [ds componentsSeparatedByString:@"."];
    if (array.count > 1) {
        NSString *lastStr = [array lastObject];
        if (lastStr.length > 2) {
            lastStr = [lastStr substringToIndex:2];
        }
        return [NSString stringWithFormat:@"%@.%@", [array firstObject], lastStr];
    }else {
        return [array firstObject];
    }
}

#pragma mark 拓展方法
/**
 加英文逗号分隔符(金额适用)，仅限整数部分
 */
+ (NSString *)addSemicolonNumber:(long)number {
    
    NSString *intStr = [NSString stringWithFormat:@"%ld", number];
    
    BOOL isNegative = NO;
    if (number < 0) {
        isNegative = YES;
        intStr = [intStr substringFromIndex:1];
    }
    
    int section = (int)intStr.length / 3;
    int remainder = (int)intStr.length % 3;
    
    NSString *targetStr;
    for (int i = 0; i <= section; i++) {
        if (i == 0) {
            if (remainder == 0) {
                targetStr = [NSString stringWithFormat:@"%@",[intStr substringToIndex:remainder]];
            }else{
                targetStr = [NSString stringWithFormat:@"%@,",[intStr substringToIndex:remainder]];
            }
        }else{
            targetStr = [NSString stringWithFormat:@"%@%@,", targetStr, [intStr substringWithRange:NSMakeRange(remainder + (i - 1) * 3, 3)]];
        }
    }
    
    NSString *tmpStr = [targetStr substringToIndex:targetStr.length - 1];
    
    if (isNegative) {
        return [NSString stringWithFormat:@"-%@",tmpStr];
    }
    return tmpStr;
}

/**
 加英文逗号分隔符(金额适用),至少保留两位小数(例:1000000000.0000>>>1,000,000,000.00    1000000000.00001>>>1,000,000,000.000001)
 */
+ (NSString *)addSemicolonLestTwoDecimals:(double)flt {
    NSString *ds = [self stringLeastTwoDecimals:flt];
    NSArray *array = [ds componentsSeparatedByString:@"."];
    NSString *intStr = [self addSemicolonNumber:[[array firstObject] longValue]];
    return [intStr stringByAppendingString:[NSString stringWithFormat:@".%@",[array lastObject]]];
}

/**
 加英文逗号分隔符(金额适用),保留两位小数(例:1000000000.0000>>>1,000,000,000.00)
 */
+ (NSString *)addSemicolonKeepDecimals:(double)flt {
    NSString *ds = [NSString stringWithFormat:@"%.2f", flt];
    NSArray *array = [ds componentsSeparatedByString:@"."];
    NSString *intStr = [self addSemicolonNumber:[[array firstObject] longValue]];
    return [intStr stringByAppendingString:[NSString stringWithFormat:@".%@",[array lastObject]]];
}

/**
 加英文逗号分隔符(金额适用),不保留小数(例:1000000000.0000>>>1,000,000,000)
 */
+ (NSString *)addSemicolonNoDecimals:(double)flt {
    NSString *ds = [self addSemicolonKeepDecimals:flt];
    return [ds substringToIndex:ds.length - 3];
}

/**
 添加单位“元”或“万元”(优惠券等福利型场景使用)，保留最后1位不为0的小数，若少于1万最多保留2位小数
 */
+ (NSString *)addUnitWelfareDecimals:(double)flt {
    if (flt >= 10000) {
        return [[DecimalsTool stringAllDecimals:flt/10000.0] stringByAppendingString:@"万元"];
    }else {
        return [[DecimalsTool stringMostTwoDecimals:flt] stringByAppendingString:@"元"];
    }
}

+ (NSString *)addUnitWelfareDecimals2:(double)flt {
    if (flt >= 10000) {
        return [[DecimalsTool stringAllDecimals:flt/10000.0] stringByAppendingString:@"万"];
    }else {
        return [[DecimalsTool stringMostTwoDecimals:flt] stringByAppendingString:@"元"];
    }
}

/**
 添加单位“万”(通用方法)，至少保留两位小数
 @param subUnit 附加单位（例：subUnit = @"元"，return @"xx元"或@"xx万元"）
 */
+ (NSString *)addUnitCommonDecimals:(double)flt subUnit:(NSString *)subUnit {
    NSString *string = nil;
    if (flt >= 10000) {
        string = [[DecimalsTool stringLeastTwoDecimals:flt/10000.0] stringByAppendingString:@"万"];
    }else {
        string = [DecimalsTool stringLeastTwoDecimals:flt];
    }
    
    if ([subUnit isKindOfClass:[NSString class]]) {
        return [string stringByAppendingString:subUnit];
    }else {
        return string;
    }
}

/**
 回报率精度处理    至少保留1位小数、小数超过4位，则从第5位四舍五入，最多保留4位
 */
+ (NSString *)rateDecimals:(double)flt {
    NSString *rateStr = [self stringLeastOneDecimals:flt];
    NSArray *array = [rateStr componentsSeparatedByString:@"."];
    
    NSString *pointStr = [array lastObject];
    
    if (pointStr.length>4) {
        return [NSString stringWithFormat:@"%.4f", flt];
    }else {
        return rateStr;
    }
}

@end