[Objective-c] NSString to NSData, NSData to NSString

// NSString to NSData

NSString *str1 = @”test”;

NSData *data1 = [str1 dataUsingEncoding:NSUTF8StringEncoding];

// NSData to NSString

NSString *str2 = [[NSString alloc] initWithData:data1 encoding:NSUTF8StringEncoding];