iOS NSData,Byte, void *, NSStrin

NSData *theData --> Byte dataByte

方式一:

theData --> NSMutableData *allData
unsigned char *dataByte = CFDataGetMutableBytePtr((__bridge CFMutableDataRef)allData); 
// unsigned char *就是Byte 的实际数据类型

方式二:
问度娘

---

Byte dataByte --> NSData *theData

方式一:

__block NSMutableData * dataM = [NSMutableData data];
[theData enumerateByteRangesUsingBlock:^(const void * _Nonnull bytes, NSRange byteRange, BOOL * _Nonnull stop) {

        [dataM appendBytes:bytes length:byteRange.length];
 }]; 

方式二:
问度娘

---

NSData *theData --> void *dataPtr

方式一:
theData --> NSMutableData *allData

void *dataPtr = allData.mutableBytes;
备注:这里不直接使用void *dataPtr = (void *)theData;
     是因为theData.bytes为(const Void *)类型,为了避免精度丢失尽可能使用同一数据类型

方式二:
待产...

---

void * --> NSData

查看NSData的相关文档即可

---

NSData *theData --> NSString *dataStr

OC中目前这种方式最靠谱:

theData --> NSMutableData *dataM
char *pChar = (char *)dataM.mutableBytes;
char arrayChar[33];// char数组的长度 = theData.length + 1,
for (int i = 0; i < theData.length; i ++) {
        
    arrayChar[i] = pChar[i];
}
arrayChar[32] = '\0';
dataStr = [NSString stringWithUTF8String:arrayChar];

---

NSData *theData --> int numInt

方式一:

theData --> NSMutableData *dataM
int *intArr = (int *)dataM.mutableBytes;
numInt = intArr[0];

方式二:

theData --> NSMutableData *dataM
int *intArr = (int *)dataM.mutableBytes;
numInt = CFSwapInt32(*theInt);