I am trying to implement kotlin multiplaform logger. During the implementation of iOS architecture, I couldn't import os.log to use os_log. How could I do this or what else can I use to log in iOS in Kotlin Multiplatform project?
The problem is that the OSLog class has only Swift API: see here. As Kotlin/Native does not provide direct interoperability, some frameworks are unavailable(see the same problem with SwiftUI for example). The best option you have out-of-the-box is to use NSLog, as Philip suggests, or to use some third-party library. There is a resource with a list of popular Kotlin Multiplatform libraries: https://github.com/AAkira/Kotlin-Multiplatform-Libraries#logging. It might be a good place to start. Two important things to note about this:
This list does not include all libraries. For sure, there are some nice libs that are not included yet.
I'm recommending it as an entry point to the community. Philips' advice is pretty good, and maybe there are some other approaches that can be seen across the libs or in the kotlinlang Slack.
You can simply use kotlin println, also in iOS part you can use platform.Foundation.NSLog for formatter output
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I want to create a Kotlin project compatible with Android and Desktop. This project needs to bind to a C library.
The way I understand it, I should create a Kotlin multiplatform project, and have a common code which wraps the C library using JNI.
However, Kotlin/Native allows a way easier interop with C libraries, so I'd like to use that. But it seems like Kotlin/Native is a platform (equal to eg jvm or android), so it can't be used as a common code.
Is there a way to do what I want? I couldn't find any simple example doing that.
If that's not possible, why? Kotlin/Native is able to target desktop and android platforms. If it's possible to use Kotlin/Native on Android, why is it impossible to use a Kotlin/Native library from a "normal" desktop/android project?
This should be possible with Kotlin Multiplatform, by having a native target.
See https://kotlinlang.org/docs/native-app-with-c-and-libcurl.html#create-a-definition-file
Kotlin/Native helps consume standard C libraries, opening up an entire ecosystem of functionality that exists for pretty much anything you may need. Kotlin/Native is already shipped with a set of prebuilt platform libraries, which provide some additional common functionality to the standard library.
UPDATE:
"common" code in Kotlin Multiplatform under the hood either:
a) has platform-agnostic Kotlin code or
b) uses expect/actual to define platform abstractions
(AFAIK)
Since a C library isn't a), you'll have to define the actual platform definitions, ending up with JNI.
TL;DR KMP isn't suitable for what you're trying to do
I read the Big Nerd Ranch guide to Kotlin and it talked in several places about Kotlin/Java interop, but never JS or native. I already had a solid background in Java, so I have gotten used to using Java classes in my Kotlin code. I am trying to write a Kotlin program which will be run on a site where most - if not all - functionality is written in JavaScript, and I am trying to understand how to write my code to make sure that it is interoperable. Will I be able to continue using Java classes in my Kotlin/JS code? What are the differences between writing Kotlin/JVM code and Kotlin/JS code? What should a (ex-) java programmer know when learning to interop with JS using Kotlin? If there are a few chapters on this in any good books written in the recent past, that would be helpful also.
As Steve already mentioned, you can't utilise java classes in Kotlin/JS.
Think of Kotlin/JS as Typescript.
It provides a different syntax to write code that ultimately compiles to JS.
Here are the notable differences of writing Kotlin/JS code vs Kotlin/JVM code
Kotlin/JS internally uses yarn for dependency management. This enables you to depend on any javascript module available on npmjs etc (see note below)
In addition to standard library, you can also leverage other kotlin-first frameworks such as kotlinx-serialization, ktor etc
Testing libraries will be JS specific. So instead of mockito / mockk / junit family, you'll need to get familiar with karma / mocha family.
There will be a difference in Coroutine capabilities - both in terms of the way one writes code and performance expectations.
I found reading about Kotlin Multiplatform helped clarify a lot about the capabilities of kotlin.
I know this was not specifically asked, but giving my 2cents to people considering Kotlin/JS (as of Sep'20)
Great if you're familiar with Kotlin and don't foresee too many third party dependencies apart from http i/o (ktor) , React ( kotlin-react) and basic html / css (covered by kotlin-styled).
Using JS modules as dependencies is not as straight forward as using JVM dependencies since there is no ready-made interop. One has to define javascript functions/classes in kotlin before using them (see here). So if you foresee leveraging a lot of existing javascript modules, it won't be an ideal way forward.
Great if you have a typical backend-frontend model where backend compiles to JVM and Frontend compiles to JS. You can leverage a common data model and http i/o framework across Backend and Frontend code (via Kotlin Multiplatform). I've found this to be a tremendous productivity boost!
Kotlin/JS compiles Kotlin code, including its own standard library, into Javascript code. At the end, that's all you have is Javascript. What you don't have is any connection to the Java Virtual Machine. Kotlin's standard library provides no magic to bridge Javascript code to the JVM so that it can utilize Java classes. So NO, you can't utilize Java classes in standard Kotlin/JS.
Hoping to hear from some more experienced developers (completely new to protobufs as of yesterday). I've been researching how to get protobufs to work with iOS given that Google doesn't have a homegrown library for objective C.
Experimenting a bit, it seems there are two general approaches:
Use a third-party library - Booyah's objective C compiler - (https://github.com/booyah/protobuf-objc).
The issue is that it won't compile with protobuf 2.5.0, and requires 2.4.1. Does anyone see a compelling reason NOT to use this method and use the older version of protobufs?
Use C++ generated protobuf classes with some tweaking - (http://www.kotancode.com/2012/10/14/using-google-protocol-buffers-in-objective-c-on-ios-and-the-mac/)
This doesn't seem like a very clean approach and C++ bleeding into objective-C code doesn't sound like fun.
On a related note, I can't find any documentation on cleanly uninstalling 2.5.0 if I opted for the former approach. What's the easiest way to do this?
Thanks.
Are there frameworks/generators for producing iOS code from any other language?
A dynamic language like JavaScript, ruby or Python are preferred. Googling for iOS code generators was largely fruitless.
The problem with systems like PhoneGap is that their output is a full-fledged application. What I need to produce is a library (.a & .h file eventually) that other Objective-C developers can reuse in their projects.
RubyMotion may or may not do what you want. I haven't seen much about the practicalities of it yet, but I'm thinking since it's statically compiled chances are good that it can produce libraries that can be simply linked into Objective-C projects. One might need another tool to produce the header files.
Of course, this is all speculation.
I think the best solution for what you're looking for is Titanium. It has its own sdk (in JavaScript), a complete IDE and allows you to have one codebase for all major platforms (iOS, Android included). What it's really awesome is the fact that it actually generates native code (a valid XCode project or a Java one for Android). It's also free and open source. Definetely worth a look.
I've never seen code generators, but there are a variety of "spoofs" as it were.
http://xamarin.com/monotouch - iOS on C#
http://phonegap.com/ - iOS on HTML, CSS , Javascript
http://ipodtoucher55.blogspot.com/2010/06/how-to-create-iphone-apps-in-flash-cs5.html - one of several tutorials for flash on iOS
I've seen links to python libraries and I think java too.
When it comes down to it though, they're all work arounds, not direct development.
I am writing a Mac OS X desktop application in which I want to be able to parse fragments of Objective-C such as variable and method declarations, as well as full Objective-C header and source files.
It looks to me as if I should be making use of Clang to do this, but I could do with some pointers and examples on how to integrate it as a library in my project, and how to invoke it to parse strings and files.
Can anyone provide me with any help on this?
You probably want libclang, code browsable at http://llvm.org/svn/llvm-project/cfe/trunk/tools/libclang/ (though you'll need to checkout the entire Clang repo to build it). There's very little documentation around on it, sadly. There is a presentation at http://llvm.org/devmtg/2010-11/Gregor-libclang.pdf that might help kickstart things, but mostly just some hunting through the code is the way to go.
Clang is actually more modular than libclang provides for (you can import just the components you want). If you've adventurous, there are examples at http://llvm.org/svn/llvm-project/cfe/trunk/examples/.