CODEWITHSUNDEEP
iosswift3unsafe-pointers
GrayFox
GrayFox

Reputation: 814

UnsafePointer<UInt8> initializer in Swift 3

I have a receipt validation class that is deprecated since Swift 3 has released. I fixed some issues, but I still have many ...

Here is the GitHub source code I used : https://gist.github.com/baileysh9/4386ea92b047d97c7285#file-parsing_productids-swift and https://gist.github.com/baileysh9/eddcba49d544635b3cf5

  1. First Error : 

        var p = UnsafePointer<UInt8>(data.bytes)

Compiler throws : Cannot invoke initializer for type UnsafePointer(UInt8) with an argument list of type UnsafeRawPointer

  1. Second error

    while (ptr < end)

Binary operators < cannot be applied to two UnsafePointer(UInt8) operands

Thank you very much in advance :)

EDIT

Thanks to LinShiwei answer I found a solution to UnsafePointer declaration. It compiles but not tested yet (because other errors avoid me to test) : 

 func getProductIdFromReceipt(_ data:Data) -> String?
{
  let tempData: NSMutableData = NSMutableData(length: 26)!
  data.withUnsafeBytes {
        tempData.replaceBytes(in: NSMakeRange(0, data.count), withBytes: $0)
    }

    var p: UnsafePointer? = tempData.bytes.assumingMemoryBound(to: UInt8.self)

Upvotes: 29

Views: 21789

Answers (3)

Jan Bergstr&#246;m
Jan Bergstr&#246;m

Reputation: 776

It is possible to put a regular pointer sign i C & in front of a Int8 array or Uint8 array to make a pointer to supply a C-function input. Like the &aBuffer array below (but the data array must copied locally first, to keep control of the storage of the data storage until finished with the operation, you get an error else). Here in a routine handling dropInteraction data (delivering a byte array):

func interpretInstanceData(filename: String, Buffer: [UInt8]) -> String {
    var aBuffer = Buffer
    let sInstanceData = String(cString: Ios_C_InterpretInstanceData(filename, &aBuffer, Int32(aBuffer.count)))

The question is slightly old. But googling for a solution on the topic of converting a swift byte array to a C-pointer (what else is UnsafePointer< UInt8 >). This question made a hit. But I think this answer is helpful for later editions of Swift (that I use). Would have worked even then. Worked in any kind of use needing a pointer from swift (just make the array of right type first).

Upvotes: 0

brw59
brw59

Reputation: 526

May have recently changed to just this, without the ".bytes." part:

var p: UnsafePointer = data.assumingMemoryBound(to: UInt8.self)

from the original:

var p = UnsafePointer<UInt8>(data.bytes)

Upvotes: -1

LinShiwei
LinShiwei

Reputation: 1062

  1. In Swift 3, you cannot init an UnsafePointer using an UnsafeRawPointer.

    You can use assumingMemoryBound(to:) to convert an UnsafeRawPointer into an UnsafePointer<T>. Like this:

    var ptr = data.bytes.assumingMemoryBound(to: UInt8.self)

  2. Use debugDescription or distance(to:) to compare two pointer.

    while(ptr.debugDescription < endPtr.debugDescription)

    or

    while(ptr.distance(to:endPtr) > 0)

Upvotes: 47

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