1 //NSData转换为UIImage  
    2 NSData *imageData = [NSData dataWithContentsOfFile: imagePath];  
    3 UIImage *image = [UIImage imageWithData: imageData];  
    4   
    5 //UIImage转换为NSData  
    6 NSData *imageData = UIImagePNGRepresentation(aimae);

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];

纯属记录!