How do I convert an NSString value to NSData? - ios

Question

How do I convert an NSString value to NSData?

Answer 1

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

Answer 2

NSString *str = #"helowrld";
// This converts the string to an NSData object
NSData *data = [str dataUsingEncoding:NSUTF8StringEncoding];
you can take reference from this link

Answer 3

Do:
NSData *data = [yourString dataUsingEncoding:NSUTF8StringEncoding];
then feel free to proceed with NSJSONSerialization:JSONObjectWithData.
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:
As documented by dataUsingEncoding::
Return Value
The result of invoking dataUsingEncoding:allowLossyConversion: with NO as the second argument
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 4

In case of Swift Developer coming here,
to convert from NSString / String to NSData
var _nsdata = _nsstring.dataUsingEncoding(NSUTF8StringEncoding)

Answer 5

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

Answer 6

First off, you should use dataUsingEncoding: instead of going through UTF8String. You only use UTF8String when you need a C string in that encoding.
Then, for UTF-16, just pass NSUnicodeStringEncoding instead of NSUTF8StringEncoding in your dataUsingEncoding: message.

Answer 7

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 8

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

Answer 9

Objective-C:
NSString to NSData:
NSString* str= #"string";
NSData* data=[str dataUsingEncoding:NSUTF8StringEncoding];
NSData to NSString:
NSString* newStr = [[NSString alloc] initWithData:theData encoding:NSUTF8StringEncoding];
Swift:
String to Data:
var testString = "string"
var somedata = testString.data(using: String.Encoding.utf8)
Data to String:
var backToString = String(data: somedata!, encoding: String.Encoding.utf8) as String!

Answer 10

Update Swift 5.x
let str = "teststring"
let data = str.data(using: .utf8)

Answer 11

Swift:
Swift 5.x
let myStringToConvert = "My String to Convert in Data"
let myData = myStringToConvert.data(using: .utf8)
String to Data:
var myStringToConvert = "My String to Convert in Data"
var myData = myStringToConvert.data(using: String.Encoding.utf8)
Data to String:
var backToMyString = String(data: myData!, encoding: String.Encoding.utf8) as String!
OBJECTIVE C:
NSString to NSData :
NSString* myStringToConvert= #"My String to Convert in Data";
NSData* myData=[str dataUsingEncoding:NSUTF8StringEncoding allowLossyConversion:NO];
NSData to NSString :
NSString* backToMyString = [[NSString alloc] initWithData: myData encoding:NSUTF8StringEncoding];

Answer 12

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

Answer 13

Objective-C
NSString *str = #"Hello World";
NSData *data = [str dataUsingEncoding:NSUTF8StringEncoding allowLossyConversion:NO];
Swift
let str = "Hello World"
let data = string.data(using: String.Encoding.utf8, allowLossyConversion: false)

Answer 14

In Swift there is an API which returns a non-optional
let str = "teststring"
let data = Data(str.utf8)