Questions tagged [unsafemutablepointer]
116 questions
10
votes
1 answer
How to use UnsafeMutablePointer in swift 4
Objective-c has a concept of a pointer to a pointer. If you dereference the first pointer you can access the original
void makeFive(int *n) {
*n = 5;
}
int n = 0;
makeFive(&n);
// n is now 5
When this is bridged to Swift 3 it becomes an…
DerrickHo328
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10
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2 answers
Swift: Cannot convert value of type 'UnsafeMutablePointer' to expected argument type 'UnsafeMutablePointer'
I have a little Problem with my Code after updating to Swift 3. I had this Code before the conversion:
extension NSData {
func castToCPointer() -> T {
let mem = UnsafeMutablePointer.alloc(sizeof(T.Type))
self.getBytes(mem, length:…
Luke Pistrol
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9
votes
2 answers
How to cast UnsafeMutableRawPointer! to UnsafeMutablePointer in Swift 3.0 or newer?
I am working with Accelerate library for my iOS app. I built this app in Swift 2.0 a couple years ago and it was working fine. Now that Swift is updated to 3.0 and 4.0, I have to convert most of the code to the current syntax. I have run the…
Keen R.D.
- 123
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8
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1 answer
Pointers in Swift
I'm trying to understand the use of pointers in Swift, in particular: Unsafe[Mutable]Pointer and UnsafeRaw[Mutable]Pointer. I have several questions on the subject.
Is UnsafePointer equal to const T * Pointer in ? and UnsafeMutablePointer …
emacos
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6
votes
1 answer
Convert UnsafeMutablePointer to UnsafePointer
I'm using a C library in my Swift project, and one of functions requires a UnsafePointer?>! as an in-out argument where I should pass my data. But the problem is that I have this data in…
Eugene Alexeev
- 1,152
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6
votes
1 answer
How to convert array to UnsafeMutablePointer Swift 3.0?
Here was my workable code in the previous version of Swift:
let imageOptionsDictKeys = [ kCVPixelBufferPixelFormatTypeKey, kCVPixelBufferWidthKey, kCVPixelBufferHeightKey, kCVPixelBufferOpenGLESCompatibilityKey,…
JULIIncognito
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6
votes
2 answers
UnsafeMutablePointer in Swift 3
I'm attempting to call SecItemCopyMatching in my keychain utility class in order to get data out of the keychain, yet I'm running into a problem with getting the result argument, UnsafeMutablePointer.
The original statement (in Swift 2,…
Jojodmo
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5
votes
2 answers
UnsafeMutablePointer.pointee and didSet properties
I got some unexpected behavior using UnsafeMutablePointer on an observed property in a struct I created (on Xcode 10.1, Swift 4.2). See the following playground code:
struct NormalThing {
var anInt = 0
}
struct IntObservingThing {
var…
kid_x
- 1,415
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5
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1 answer
Swift UnsafeMutablePointer: Must I call deinitialize before deallocate?
Given an instance of UnsafeMutablePointer, what's the point of calling deinitialize(count:) right before deallocate(capacity:)?
Can't you just call deallocate(capacity:)?
I saw this when reading the section "Using Typed Pointers" of the article…
ma11hew28
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5
votes
2 answers
Testcase failed after converting codes from Objective-C to Swift
I am doing some bitwise operations in Swift style, which these codes are originally written in Objective-C/C. I use UnsafeMutablePointer to state the beginning index of memory address and use UnsafeMutableBufferPointer for accessing the element…
Zigii Wong
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4
votes
1 answer
UnsafeMutablePointer to an Array element
var a = [1,2,3]
let ptr1 = UnsafeMutablePointer(&a[0]) //works fine
let index = 0
let ptr2 = UnsafeMutablePointer(&a[index]) //compiler throws error
error: cannot invoke initializer for type UnsafeMutablePointer with an argument…
jblixr
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4
votes
4 answers
Why a struct declared by let can be changed?
In the following code, 'ptr' is a struct declared by let, but its member variable 'pointee' could be changed, Why?
let ptr = UnsafeMutablePointer.allocate(capacity:1)
ptr.pointee = 1
Laughing
- 85
- 6
4
votes
1 answer
Swift deallocate vs free usage
I am allocating bytes using the following call in Swift 3:
let wordSize = 2
let numbytes = 1024*wordsize
var ptr = UnsafeMutableRawPointer.allocate(bytes: numbytes, alignedTo: wordSize)
Question is whether it is correct to deallocate the memory,…
Deepak Sharma
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4
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3 answers
Mutual non-optional reference cycle in Swift
Consider the following use case:
In a model for some game, you have a Player class. Each Player has an unowned let opponent: Player which represents the opponent they are playing against. These are always created in pairs, and a Player must always…
Jumhyn
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4
votes
2 answers
Using C functions in Swift that take functions as arguments
I'm writing a wrapper around a C mathematical library. Every function takes one or two functions as arguments. However, the arguments for those child functions (as well as the parent functions) are not Swifty -hence the wrapper.
I've cleaned up the…
Adam Jones
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