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How to append the bytes of a bit-field to NSMutableData

开发者 https://www.devze.com 2023-04-02 01:39 出处:网络
I have a struct typedef struct { int8_t foo: 1; } Bar; I have tried to append the bytes to a NSMutableData object like so:

I have a struct

typedef struct {
   int8_t foo        : 1;
} Bar;

I have tried to append the bytes to a NSMutableData object like so:

NSMutableData* data = [[N开发者_高级运维SMutableData alloc] init];
Bar temp;
temp.foo = 1;
[data appendBytes:&temp.foo length:sizeof(int8_t)];

But I receive an error of Address of bit-field requested. How can I append the bytes?


Point to the byte, mask the needed bit, and append the variable as a byte:

typedef struct {
    int8_t foo: 1;
} Bar;

NSMutableData* data = [[NSMutableData alloc] init];
Bar temp;
temp.foo = 1;

int8_t *p = (int8_t *)(&temp+0);    // Shift to the byte you need
int8_t pureByte = *p & 0x01;       // Mask the bit you need
[data appendBytes:&pureByte length:sizeof(int8_t)];
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