计算NSString中英文字符串的字符长度，及按字符长度截取

charNumber

//计算NSString中英文字符串的字符长度。ios 中一个汉字算2字符数
- (int)charNumber:(NSString*)strtemp
{
    int strlength = 0;
    char* p = (char*)[strtemp cStringUsingEncoding:NSUnicodeStringEncoding];
    for (int i = 0; i < [strtemp lengthOfBytesUsingEncoding:NSUnicodeStringEncoding]; i++) {
        if (*p) {
            p++;
            strlength++;
        } else {
            p++;
        }
    }
    return strlength;
}

    // 按字节截取字符串
    if ([self charNumber:coopBoxName] > 12) {
        NSString* tmp;
        for (int i = coopBoxName.length; i > 0; i--) {
            tmp = [coopBoxName substringToIndex:i];
            if ([self charNumber:tmp] <= 9) {
                coopBoxName = [tmp stringByAppendingString:@"..."];
                break;
            }
        }
    }