Round numbers to Units 102.000 to 102K 9.900 to 9.9K 1.000.200 to 1M

NBUnitsNumberFormatter.m

#import "NBUnitsNumberFormatter.h"

@implementation NBUnitsNumberFormatter

- (NSString *)stringForObjectValue:(id)value; {
  if (![value isKindOfClass:[NSNumber class]]) {
    return nil;
  }
  return [self stringForFloat:[value floatValue]];
}

- (NSString *)stringForFloat:(float)v {
  NSString *unit;
  
  float rounded = v;
  float m = 0.0;
  
  NSNumberFormatter *formatter = [[NSNumberFormatter alloc] init];
  [formatter setMaximumFractionDigits:1];

  if (v <= 999) {
    return [NSString stringWithFormat:@"%.0f", v];
  }
  else if (v >= 1000 && v < 1000000) {
    m = fmod(rounded, 1000);
    rounded = rounded / 1000.0;
    if (m < 100 || rounded > 99) {
      [formatter setMaximumFractionDigits:0];
    }
    unit = @"K";
  }
  else if (v >= 1000000) {
    m = fmod(rounded, 1000000);
    rounded = rounded / 1000000.0;
    if (m < 100000 || rounded > 99)  {
      [formatter setMaximumFractionDigits:0];
    }
    unit = @"M";
  }
  
  [formatter setRoundingMode:NSNumberFormatterRoundFloor];
  NSString *val = [formatter stringFromNumber:[NSNumber numberWithFloat:rounded]];
  return [NSString stringWithFormat:@"%@%@", val, unit];
}

@end