请有人指导我如何从NSData创建字节数组,这是我的创建NSData的代码。
NSData* data = UIImagePNGRepresentation(img);
unsigned char *bytes = [data bytes];
// Make your array to hold the bytes
NSUInteger length = [data length];
unsigned char *bytes = malloc( length * sizeof(unsigned char) );
// Get the data
[data getBytes:bytes length:length];
NB 别忘了 - 如果你复制了数据,也必须在某个时刻调用 free(bytes)
;)
UInt8 *bytes = (UInt8 *)[data subdataWithRange:(NSRange){0,length}].bytes
- Marcin这是获取数组最快的方式(但比较危险):
unsigned char *bytesArray = data.bytes;
NSUInteger lengthOfBytesArray = data.length;
在尝试获取第100个字节之前,您应该检查bytesArray的长度,例如:
if (lengthOfBytesArray > 100 + 1)
{
unsigned char byteWithOffset100 = bytesArray[100];
}
还有一种更安全、更像Objective-C的方式:
- (NSArray*) arrayOfBytesFromData:(NSData*) data
{
if (data.length > 0)
{
NSMutableArray *array = [NSMutableArray arrayWithCapacity:data.length];
NSUInteger i = 0;
for (i = 0; i < data.length; i++)
{
unsigned char byteFromArray = data.bytes[i];
[array addObject:[NSValue valueWithBytes:&byteFromArray
objCType:@encode(unsigned char)]];
}
return [NSArray arrayWithArray:array];
}
return nil;
}