Use of unresolved identifier 'sizeof'

Question

I'm trying to send a position between two devices, so I need to convert the position to NSData. I found something on the net but I have an error: Use of unresolved identifier 'sizeof'. I don't know how to solve, could you help me?. Here's my code:

var error: Error?
    var positionToSend = car.position
    let dataSend = NSData(bytes: &positionToSend, length: sizeof(CGPoint))
    try? match.sendData(toAllPlayers: dataSend, with: .unreliable)
    if error != nil {
    }

For sizeof see [Swift: How to use sizeof?](https://stackoverflow.com/a/27640066/1187415). – Using the approach from [round trip Swift number types to/from Data](https://stackoverflow.com/q/38023838/1187415) it would be `let dataSend = Data(buffer: UnsafeBufferPointer(start: &positionToSend, count: 1))` — Martin R, Jul 21 '18 at 17:01

vadian · Answer 1 · 2018-07-21T17:10:12.750

1

First of all the error variable is pointless. try? doesn't affect error at all.

sizeof has been changed to MemoryLayout.size(ofValue:. The argument is positionToSend, not the type CGPoint

The Swift 3+ way to create Data (not NSData) from a CGPoint is

let dataSend = Data(bytes: &positionToSend, count: MemoryLayout.size(ofValue: positionToSend))

edited Jul 21 '18 at 17:10

answered Jul 21 '18 at 16:46

vadian

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You don't need the `UnsafePointer()` – Martin R Jul 21 '18 at 17:00

score 1 · Accepted Answer · answered Jul 21 '18 at 17:07

1

I would rewrite your code in Swift 4 as:

var positionToSend = car.position
let dataSend = Data(bytes: &positionToSend, count: MemoryLayout.size(ofValue: positionToSend))
do {
    try match.sendData(toAllPlayers: dataSend, with: .unreliable)
} catch {
    //Write code for `if error != nil`...
    print(error)
}

You do not need withUnsafePointer.

answered Jul 21 '18 at 17:07

OOPer

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Excuse me, and If I want to receive this data sent? – Andrea Culot Jul 21 '18 at 23:21
@AndreaCulot, it depends on many things. Have you got the received data as `Data`? Or something else? – OOPer Jul 22 '18 at 00:38
Seems you have started a new thread now. There are many readers who can help you. – OOPer Jul 22 '18 at 00:40

Use of unresolved identifier 'sizeof'

2 Answers2