I couldn't manage to find an answear to this question. Is Swift just an Objective-C wrapper, where Swift code is turned into objective-c when the code compiles?
no, it is made into llvm bytecode or -as pointed out by delnan- as it called today llvm bitcode
"[The new term is used] partly to break association with bytecode as employed by traditional virtual machines (because LLVM IR is very much different from that)"
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I want to import a Swift framework called "Beethoven" into Objective-C project. I import this framework via cocoapods.
The problem is that framework is written in pure swift. Since the classes are not subclass of NSObject they can't be used directly in my objC classes.
I am newbie in Swift and intermediate in objC, but I think there may be 2 solutions for that:
1-Modifying the whole library: which is probably not an optimal solution.
2-Using a new class which behaves as an interface between swift framework and my objC code. I think second solution will be a better alternative in terms of time and effort needed.
Actually below given post explains modifying the pure swift classes but I don't know how to apply this in my case.
How to use Swift non-NSObject subclass in Objective-C
As I mentioned I am not a very capable programmer and there may be better solutions for that problem. I would be grateful if someone can help me and suggest the best solution for integrating pure Swift framework into my objC project.
NSObject is usually not the only problem. Swift has many features that are not supported by Objective-C. To name a few: swift value types (struct's), swift enums with attached values. If a library uses any of those, it will not be possible to auto-generate an Objective-C header (.h) for it.
Adapting the code of the library on the spot might work, but it is likely more work long term in case if you ever need to update that library again.
Your 2nd approach sounds better: create a layer that is compatible with Objective-C on top of the library which exports methods that need to be exported with #objc and adapts the types. If you go that way consider making a PR contribution to the original library so that everyone could use it in Objective-C projects, and you share responsibility of updating it when the swift code changes.
The 3rd approach would be actually to rewrite some parts of you app to Swift. That might or might not be easier depending on the size of the part of the app that is using the library and how well it is isolated from the rest of the app.
I am building a new framework. The project is to be coded into Swift language, however the clients using this framework have the freedom of using either swift or Objective-C framework.
The question is how do I start. There could be numerous issues like
using structs in swift code but it cannot be made available in
objective C framework.
optionals are missing objective c
Even if I
write different set of files for Swift and Objective C, how will I
map them onto different frameworks under the same project.
Enums with other than Int as rawValue can't be used.
Tuples would not work
I know there have been a few questions around this but none have any satisfactory answer.
PS - Any link to a tutorial or blog would be super helpful too
I did this and got some unexpected results: I have trouble integrating the framework in Swift application. Objective-C works just fine.
You mentioned some of the caveats here.
I suggest doing this iteratively while writing test application in Objective-C which uses all the features. This way if there is some feature that does not cross Swift to Objective-C boundary well, it will be discovered as early as possible.
Your remarks about issues are generally correct with one small exception: optionals are not missing from Objective-C, they appear as nullable/nonnull modifiers on variables and method parameters. Although this does not replace optionals fully, it helps detecting issues early in the process.
Here is a random list of some other issues I discovered:
Bridging between Swift Error and NSError used in Objective-C. The conversion is not always as smooth at it could be, so better use NSError in exported code.
If you mix Objective-C and Swift in your framework, you cannot use bridging header, instead using modulemap files which tend to turn pretty large and complex.
Since you cannot embed frameworks inside a framework, you have to make sure that the application sets ALWAYS_EMBED_SWIFT_STANDARD_LIBRARIES flag for its target. This has to be clearly indicated in the documentation. Also, when creating fat library for your framework, you have to strip these files from the distributed SDK.
And, as I said in the beginning, I still have no success using the resulting mixed language framework in Swift application.
Hope, this will add to your list of things to take into account when developing the library.
If I create an Xcode project with the iOS Single View Application template and choose Swift for the language, will the compiler exclude from the release build (binary) functions that never get called?
I'm wondering because I want to include a third-party library that has a lot of superfluous classes & functions, and I want to keep my app small & fast.
While I agree with comments, it is unlikely to impact performance in any significant way even if it was included...
Xcode 6 uses Apple LLVM Compiler Version 6.1, depending on how closely related it is to LLVM Developer Group's version the optimization feature is available http://llvm.org/docs/Passes.html with options such as -dce: Dead Code Elimination, -adce: Aggressive Dead Code Elimination.
One way to know for sure what is included is checking the assembly output using -emit-assembly option in the swift compiler and review the output, or opening the binary in a disassembler such as Hopper ( http://www.hopperapp.com/download.html )
Can we create iOS app with swift and obj c both.My half app is made using OBJ-C and just want to improve apps performance so is that possible to use swift in between
Yes you can.
You have to add objc header #imports in the <module name>-Bridging-Header.h that you want to make available in swift, and you can use swift code from objc by importing the <module name>-Swift.h file in your objc code.
Note that the latter header file is automatically generated when building, and it is not visible in the project navigator - but you can open it by cmd+click-ing its name in an existing #import. Also to note that if compilation fails, most likely the file will not be generated.
Last, I highly recommend that you avoid circular references between objc and swift - for instance, creating a SwiftClass, inherited from BaseObjcClass, and using SwiftClass from objc - I've experienced that it doesn't work (compilation errors), and I am not aware of any workaround
Yes, you can. You just need to follow this:
https://developer.apple.com/library/ios/documentation/Swift/Conceptual/BuildingCocoaApps/MixandMatch.html
Apple’s intention to replace the Objective-C language using Swift, it is not practical in the short term simply due to the fact that developers are deeply entrenched in Objective-C. Rather than force Swift down the developer’s throat, Apple has made it easy to allow Objective-C to interoperate with Swift.
http://mobiforge.com/design-development/using-objective-c-and-swift-together-ios-apps
Dec 2018 - I found this useful YouTube video that helps explain what files you need to add and how to make the connections.
YouTube - How to use Swift and Objective-C in the same project
I am a game developer. I have developed a game using box2d which is in Final Phase. To structure the code when i attempt to make code refactoring i am receiving this error alert http://screencast.com/t/ir1nCvnx . But when i attempt to make code refactoring for another project which is not using .mm suffix means i can make it out. The thing i want to know is can we do code refactoring for the code using c++ concepts. If not what is other way to do code refactoring.
I thought because Xcode depended on the clang front end for all of its
code coverage features, that it would eventually be able to refactor
C++. As I understood it, it didn't refactor C++ in the past because
clang's C++ support was still insufficient.
But clang is a very good C++ compiler now. Yet Xcode still balks at
even renaming symbols (the only refactoring I've ever needed).
So, till now, you can not refactor your C++ code and hope you will get it with new release of clang / LLVM / XCode.