[swift-users] changes to pointer data types in Xcode 8 beta 6

[Zach Waldowski]

Nerd here!

That part of the code ends up not needing to go through the
UnsafeRawPointer API, as it's processing UTF-8 bytes, see also:
<https://github.com/bignerdranch/Freddy/pull/191>.

That being said, good resources for reading about the new pointer system
are:
- [SE-0107]:
<https://github.com/apple/swift-evolution/blob/master/proposals/0107-unsaferawpointer.md>
- [The Apple API reference], once it's updated:
<https://developer.apple.com/reference/swift>

You can also look up the documentation using the "Documentation and API
Reference" menu in Xcode 8 Beta 6, as it's currently updated.

Sincerely,
  Zachary Waldowski
  zachary at bignerdranch.com

On Mon, Aug 15, 2016, at 03:05 PM, Dave Reed via swift-users wrote:
> I'm trying to convert the following code (from the Big Nerd Ranch's
> Freddy JSON parser) that works in Xcode 8 beta 5 and convert it to work
> with beta 6. Essentially it appears it needs to take a Data object and
> convert it to a UnsafeBufferPointer<UInt8> if I understand it correctly.
> 
> 
>     /// Creates a `JSONParser` ready to parse UTF-8 encoded `NSData`.
>     ///
>     /// If the data is mutable, it is copied before parsing. The data's
>     lifetime
>     /// is extended for the duration of parsing.
>     init(utf8Data inData: Data) {
>         let data = (inData as NSData).copy() as! Data
>         let buffer = UnsafeBufferPointer(start:
>         UnsafePointer<UInt8>((data as NSData).bytes), count: data.count)
>         self.init(buffer: buffer, owner: data)
>     }
> 
> And this case appears to be going from a String to
> UnsafeBufferPointer<Uint8>
> 
> 
>     /// Creates a `JSONParser` from the code units represented by the
>     `string`.
>     ///
>     /// The synthesized string is lifetime-extended for the duration of
>     parsing.
>     init(string: String) {
>         let codePoints = string.nulTerminatedUTF8
>         let buffer = codePoints.withUnsafeBufferPointer {
>         nulTerminatedBuffer in
>             // don't want to include the nul termination in the buffer -
>             trim it off
>             UnsafeBufferPointer(start: nulTerminatedBuffer.baseAddress,
>             count: nulTerminatedBuffer.count - 1)
>         }
>         self.init(buffer: buffer, owner: codePoints)
>     }
> 
> }
> 
> 
> I understand pointers from my C/C++/Objective-C days but I don't yet
> understand the various Swift pointer types. Any help is appreciated.
> 
> Note: I don't work for Big Nerd Ranch. I'm just trying to use the code
> and better understand the various Swift pointer types.
> 
> Thanks,
> Dave Reed
> 
> 
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