static NSString const base55Chars = 23456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghjkmnpqrstuvwxyz;+ NSString convertToBase55longnumber NSInteger base = 55; NSMutableString result = NSMutableString s

static NSString * const base55Chars = @"23456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghjkmnpqrstuvwxyz";

• (NSString *)convertToBase55:(long)number { NSInteger base = 55; NSMutableString *result = [NSMutableString string];

  while (number > 0) { NSInteger remainder = number % base; NSString *character = [base55Chars substringWithRange:NSMakeRange(remainder, 1)]; [result insertString:character atIndex:0]; number /= base; }

  return result; }

• (long)convertFromBase55:(NSString *)base55String { NSInteger base = 55; long result = 0;

  for (NSInteger i = 0; i < base55String.length; i++) { NSString *character = [base55String substringWithRange:NSMakeRange(i, 1)]; character = [character uppercaseString]; // 将字符转换为大写 NSInteger value = [base55Chars rangeOfString:character].location; result = result * base + value; }

  return result;