17.9.22 更新...

1. 这个类NSNumberFormatter

    NSNumberFormatter *moneyFormatter = [[NSNumberFormatter alloc] init];
    moneyFormatter.positiveFormat = @"###,##0.00";
    NSString *formatString = [moneyFormatter stringFromNumber:@(1234567.123)];

效果入下图

image.png

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下边这个方法太麻烦... 直接用上边这个方法吧

2.先取保留俩位小数, 再传入对应 string 传入 111111.09 得到 111,111.09 系统自带的转换方法有时候小数位计算不准确

- (NSString *)separatedDigitStringWithStr:(NSString *)digitString {
    if (digitString.length <= 3) {
        return digitString;
    } else {
        NSMutableString *processString = [NSMutableString stringWithString:digitString];
        int location = processString.length - 3;
        NSMutableArray *processArray = [NSMutableArray array];
        while (location >= 0) {
            NSString *temp = [processString substringWithRange:NSMakeRange(location, 3)];
            [processArray addObject:temp];
            if (location < 3 && location > 0) {
                NSString *t = [processString substringWithRange:NSMakeRange(0, location)];
                [processArray addObject:t];
            }
            location -= 3;
        }
        NSMutableArray *resultsArray = [NSMutableArray array];
        int k = 0;
        for (NSString *str in processArray) {
            k++;
            NSMutableString *tmp = [NSMutableString stringWithString:str];
            if (str.length > 2 && k < processArray.count ) {
                [tmp insertString:@"," atIndex:0];
                [resultsArray addObject:tmp];
            } else {
                [resultsArray addObject:tmp];
            }
        }
        NSMutableString *resultString = [NSMutableString string];
        for (int i = resultsArray.count - 1 ; i >= 0; i--) {
            NSString *tmp = [resultsArray objectAtIndex:i];
            [resultString appendString:tmp];
        }
        NSRange range = NSMakeRange(resultString.length - 4, 1);
        [resultString deleteCharactersInRange:range];
        return resultString;
    }
}