Is it possible to write inline assembly in Swift?

Question

I was wondering if you can write inline assembly in Swift.

I know that in Objective-C you could use something like this:

inline void assemblyFunc() {
    __asm__(/*Assembly*/);
}

But in Swift it seems that you can't use __asm__(/*Assembly*/).

Does anyone know how to use __asm__() if its even possible. I haven't found anything about it, so I thought it would be a good question to ask.

There's no inline asm support. Please report a bug if this feature is important to you. — Stephen Canon, Jun 16 '14 at 15:03
the _Swift_ is mostly designed for the entry-level developers on iOS platform. — holex, Jun 16 '14 at 15:04
@holex I don't think so. Swift is designed to be more expressive and make developers more productive in the cases where performance is not the number 1 priority, which is most of them — Jiaaro, Jun 16 '14 at 15:16
Nowhere in Apple's developer or marketing materials for Swift do they say it's only or primarily for new developers. As @Jiaaro notes, it's designed to increase productivity for all developers. (And it's designed to be fast, even if it's not always so in the beta.) — rickster, Jun 16 '14 at 15:20
"The focus of Swift 1.0 is definitely on improving general app development, but we do expect Swift to grow capabilities (e.g. perhaps even the ability to write inline assembly code)" - [Apple Developer Forums](https://devforums.apple.com/message/1007178#1007178) — griotspeak, Jun 19 '15 at 23:28
Possible duplicate of [calling a function defined in assembly from swift](https://stackoverflow.com/questions/39420513/calling-a-function-defined-in-assembly-from-swift) — Sapphire_Brick, Oct 23 '19 at 01:26
@Sapphire_Brick How can this question be a duplicate when it was asked before the question you linked? — Bas, Oct 28 '19 at 11:21

score 14 · Accepted Answer · edited Jul 11 '23 at 01:44

14

To expand on what Robert Levy said, you can just use the Swift/Obj-C interop feature, and write an Obj-C class that does the ASM stuff, which you can then call from Swift.

It's an annoying workaround, but it should work nonetheless.

You can read more about how to do ObjC-to-Swift interop here

edited Jul 11 '23 at 01:44

Phil Dukhov

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answered Jun 16 '14 at 15:12

Electric Coffee

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Are you just repeating Robert Levy's answer? – Jean-Philippe Pellet Jun 16 '14 at 17:39
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No, he's building on it. Robert didn't exactly explain what to do, just to "take advantage" of a feature. Electric Coffee actually explained the solution, what steps the questioner should take. – mginn Jun 16 '14 at 19:02
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@milesper the "explanation" being "write an ObjC class"? Darn, I forgot to include that clarification – Robert Levy Jun 16 '14 at 19:04
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I've further expanded my answer a bit – Electric Coffee Jun 16 '14 at 21:55

score 13 · Answer 2 · answered Jun 16 '14 at 15:00

13

There isn't a way in Swift itself. If you need this, probably a good opportunity to take advantage of Swift-ObjC interop.

answered Jun 16 '14 at 15:00

Robert Levy

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More here https://developer.apple.com/documentation/swift/importing-objective-c-into-swift – wieczorek1990 Mar 10 '23 at 09:00

Is it possible to write inline assembly in Swift?

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