iOS NSString 和NSData 转换

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];