NSString 转 Data 转 char 转 NSDicti

1. 字符串转Data 
NSString * str =@"str"; 
NSData *data =[str dataUsingEncoding:NSUTF8StringEncoding]; 

2.NSData 转NSString 
NSString * str  =[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]; 

3.data 转char 
NSData *data;  
char * haha=[data bytes]; 

4. char 转data  
byte * byteData = malloc(sizeof(byte)*16);  
NSData *content=[NSData dataWithBytes:byteData length:16];

5. data 转NSDictionary  
NSDictionary *myDictionary = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:nil];