How do I convert an NSString value to NSData?

Question

How do I convert an NSString value to NSData?

Answer 1

NSString* str = @"teststring";
NSData* data = [str dataUsingEncoding:NSUTF8StringEncoding];

Answer 2

NSString *str = @"hello";
NSData *data = [NSData dataWithBytes:str.UTF8String length:str.length];

Answer 3

For Swift 3, you will mostly be converting from String to Data.

let myString = "test"
let myData = myString.data(using: .utf8)
print(myData) // Optional(Data)

Answer 4

NSString *str = @"Banana";
NSData *data = [str dataUsingEncoding:NSUTF8StringEncoding allowLossyConversion:true];

Answer 5

Do:

NSData *data = [yourString dataUsingEncoding:NSUTF8StringEncoding];

then feel free to proceed with NSJSONSerialization:JSONObjectWithData.

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Correction to the answer regarding the NULL terminator

Following the comments, official documentation, and verifications, this answer was updated regarding the removal of an alleged NULL terminator:

1. As documented by dataUsingEncoding::

   Return Value

   The result of invoking dataUsingEncoding:allowLossyConversion: with NO as the second argument

2. As documented by getCString:maxLength:encoding: and cStringUsingEncoding::

   note that the data returned by dataUsingEncoding:allowLossyConversion: is not a strict C-string since it does not have a NULL terminator

Answer 6

Objective-C:

NSString *str = @"test string";
NSData *data = [NSKeyedArchiver archivedDataWithRootObject:str];
NSString *thatStr = [NSKeyedUnarchiver unarchiveObjectWithData:data];

Swift:

let str = "test string"
let data = NSKeyedArchiver.archivedData(withRootObject: str)
let thatStr = NSKeyedUnarchiver.unarchiveObject(with: data) as! String