CSData

NSString 转换成NSData 对象

NSData* xmlData = [@"testdata" dataUsingEncoding:NSUTF8StringEncoding];

NSData 转换成NSString对象

NSData * data;
NSString *result = [[NSString alloc] initWithData:data  encoding:NSUTF8StringEncoding];

NSData 转换成char*

NSData *data;
char *test=[data bytes];

char* 转换成NSData对象

byte* tempData = malloc(sizeof(byte)*16);
NSData *content=[NSData dataWithBytes:tempData length:16];