在没有NSString的情况下使用带有NSData的Swift字符串

Question

Is it possible to init a Swift string (not NSString ) with the contents of an NSData object without creating an NSString first?

I know I can use this with NSString:

var datastring = NSString(data data: NSData!, encoding encoding: UInt)

But how can I use a basic Swift String type? I thought Swift strings and NSStrings were interchangeable, do I really have to get the data out of NSData using NSString and then assign that value to a Swift string?

Answer 1

As of Swift 1.2 they aren't quite interchangeable, but they are convertible, so there's really no reason not to use NSString and its constructors when you need to. This will work fine:

var datastring = NSString(data:data, encoding:NSUTF8StringEncoding) as! String

The as! is needed because NSString(...) can return nil for invalid input - if you aren't sure that the data represents a valid UTF8 string, you may wish to use the following instead to return a String? (aka Optional<String> ).

var datastring = NSString(data:data, encoding:NSUTF8StringEncoding) as String?

Once constructed, you can then use datastring just like any other Swift string, eg

var foo = datastring + "some other string"

Answer 2

var buffer = [UInt8](count:data.length, repeatedValue:0)
data.getBytes(&buffer, length:data.length)
var datastring = String(bytes:buffer, encoding:NSUTF8StringEncoding)

Answer 3

In Swift 2.0 You can do something like this:-

import Foundation

var dataString = String(data: YourData, encoding: NSUTF8StringEncoding)

In Swift 3.0 :-

import Foundation

var dataString = String(data: data, encoding: String.Encoding.utf8)