CODEWITHSUNDEEP
iosarraysswift
Vyacheslav
Vyacheslav

Reputation: 27211

UnsafeMutablePointer for array using in C library

I want to implement C library into my iOS project. I'm using swift language.

I have a function where the input parameter - where output values are stored - is ar usual C double array: 

double ar[6];
///...
 err = c_lib_func(ar);

If I initialize inside swift like var ar: [Double] xCode says I have to use

UnsafeMutablePointer. But inside the docs I haven't found how to initialize n-lenght array for UnsafeMutablePointer. I just can do something like this: var ar : UnsafeMutablePointer<Double>. But I can understand how to initialize it as 6-length array. Please, help me.

If I'm using 

ar = [Double]
err = c_lib_func(ar);

the xCode shows to me this error:

/Users/admin/Documents/projects/myApp/myApp/file.swift:46:46: Cannot convert value of type '[Double]' to expected argument type 'UnsafeMutablePointer'

Upvotes: 0

Views: 460

Answers (1)

Robert Gummesson
Robert Gummesson

Reputation: 5666

In Swift, [Double] is an array of double values which is not what you are after. If you want to initialize an UnsafeMutablePointer you can just use:

var ar = UnsafeMutablePointer<Double>.alloc(6)

Use ar.dealloc(6) to release the memory again.

Upvotes: 1

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