@interface NSString (Helper)

/**
 *  截取小數(shù)點(diǎn)位數(shù),最多保留digit位,且小數(shù)點(diǎn)后多余的0將被去掉.
 *
 *  @param digit 小數(shù)點(diǎn)后最多保留位數(shù)
 *
 *  @return 返回一個(gè)截取后的小數(shù)字符串對(duì)象
 */
- (NSString *)floatStringTruncateWithMaxReservedDecimalPointDigit:(NSInteger)digit;

@end

@implementation NSString (Helper)

- (NSString *)floatStringTruncateWithMaxReservedDecimalPointDigit:(NSInteger)digit
{
    if (self.length == 0) {
        return @"0";
    }
    
    if ([self rangeOfString:@"."].length == 0) {    //不是小數(shù)
        return self;
    }
    
    NSMutableString *formatString = [NSMutableString stringWithString:@"%.f"];
    [formatString insertString:[NSString stringWithFormat:@"%ld", (long)digit] atIndex:2];
    NSString *truncatedStr = [NSString stringWithFormat:formatString, self.floatValue];
    NSString *rs = [NSString stringWithFormat:@"%@", @(truncatedStr.floatValue)];
    return rs;
}

@end