转换＆QUOT;弦乐＆QUOT;二进制到文字的NSString

问题描述

我能够一个NSString转换（ASCII）文本二进制数的NSString，但我有麻烦做相反。例如：你好变成01101000 01101001

I am able to convert an NSString of (ASCII) text to a NSString of binary numbers, but I am having troubles doing the opposite. For example: "Hi" becomes "01101000 01101001".

I need: "01101000 01101001" to become "Hi".

我在寻找最实施这种直接的方式。注意二进制数的每8位之间的空间。

I'm looking for the most direct way to implement this. Note the space between every 8 bits of binary numbers.

推荐答案

考虑到格式的总是的那样，这code应该工作：

Considering the format is always like that, this code should work:

NSString *
BinaryToAsciiString (NSString *string)
{
    NSMutableString *result = [NSMutableString string];
    const char *b_str = [string cStringUsingEncoding:NSASCIIStringEncoding];
    char c;
    int i = 0; /* index, used for iterating on the string */
    int p = 7; /* power index, iterating over a byte, 2^p */
    int d = 0; /* the result character */
    while ((c = b_str[i])) { /* get a char */
        if (c == ' ') { /* if it's a space, save the char + reset indexes */
            [result appendFormat:@"%c", d];
            p = 7; d = 0;
        } else { /* else add its value to d and decrement
                  * p for the next iteration */
            if (c == '1') d += pow(2, p);
            --p;
        }
        ++i;
    } [result appendFormat:@"%c", d]; /* this saves the last byte */

    return [NSString stringWithString:result];
}

告诉我，如果它的某些部分是不清楚。

Tell me if some part of it was unclear.

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