I am very new to iOS who is trying to use swift in objective-c. I created a swift class in the objective-c project and i am able to call that class from an objective-c view controller.
The problem is if i make any changes in the swift code, it doesn't seem to be available immediately for objective-c class to access. Each time i change something in the swift class, i will have to build the project and only then it seems to be available in objective-c.
Is there a configuration that i am missing or it is expected to work this way by design?
Please read this explanation from apple. Read the sub-heading "Importing Swift into Objective-C". The generation of header files might be the explanation for your issue.
https://developer.apple.com/library/ios/documentation/Swift/Conceptual/BuildingCocoaApps/MixandMatch.html#//apple_ref/doc/uid/TP40014216-CH10-ID122.
Related
I've been the last week trying to serialise all of the classes of one iOS project (Objective-C).
Due to I use to do it in Android projects with Avro (Apache) library, I've been trying to do the same in the iOS project, however, the first thing that I noticed is that there is not too much information about Avro in iOS.
First thing I tried:
Implement the library ObjectiveAvro using CocoaPods but some classes in the library Avro C were not found when imported.
Second thing I tried:
Remove and do again the previous process but this time only with the Avro C library but the same error appeared.
Third thing I tried:
Implement BlueSteel framework using Carthage. This is a swift library but I wanted to try if I could use it somehow in an Objective-C project. I couldn't.
I just need to serialise and deserialise data providing a schema as you can do with Avro (Android) in an Objective-C project and the last thing that I want to do is convert the whole project to Swift.
So do you know what's the current way to do that in Objective-C?
I could figure it out how to do the Third thing I tried:
Basically, it's necessary to import the library through Carthage, then create a new Swift class which is the one that is going to "talk" with the Swift library, due to we are in an Objective-C project. XCode will ask you to add a "header-class" and press "yes".
Then it's as simple as using the Swift to call the library methods and call the Swift class from the current classes. Swift class in Objective-C project
Finally just to inform that the BlueSteel framework is a nightmare due to is really limited and really poor documented therefore I still don't know a real alternative.
However, if you're going to use it, have in mind that the classes are not autogenerated so you need to do manually the conversion to Avro and sign results.
I create new project with CocoaPods (Xcode 9.3.1 and Swift 4.1)and of course use SnapKit in it.
and I want use third party class TreeView ,this class wrote by Objc.
How cloud I use SnapKit in class TreeView ???
I try to use the following steps but not working:
create new file named SnapKit-Bridging-Header.h
go to TreeView.m , import the header file (notice:It ends with '-Swift'):
#import "SnapKit-Swift.h"
compiling now is OK! and I can see LayoutConstraint (defined in SnapKit)and some other class in TreeView.m file
but when I use view.snp.xxx ,it complain "Property 'snp' not found ..."
So my Q is How could I use view.snp.xxx in ObjC file??? Thanks :)
Swift code is not fully interoperable with Objective-C.
You can only use such Swift elements in your bridging header that are supported by Objective-C. This library requires Swift, it doesn't say that it supports Objective-C, so it's likely you need to do extra adaptation efforts to support it.
In iOS 9+ you have NSLayoutAnchor API that is almost as easy to use as SnapKit
(see https://developer.apple.com/library/content/documentation/UserExperience/Conceptual/AutolayoutPG/ProgrammaticallyCreatingConstraints.html ;
https://cocoacasts.com/working-with-auto-layout-and-layout-anchors/ ; https://theswiftlibrary.com/the-simple-way-of-creating-constraints-in-code)
This API is easy to use and compatible with Objective-C.
If you want to support iOS 8, you can use a backporting library like this one.
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.
Actually, I am working on one app and started with the objective-c. Now i have started working on swift with the same app for the further development and it will work with both the class (objc and swift).
Now I have doubt that it will accept by apple store or not.
Please help me.
This is fine, Apple provides the mechanisms for interacting with both and will not drop support for Objective-C for quite sometime. Many large organisations still have the majority of their code written in Obj-C (including Apple) so they need to give people time to transition, they aren't going to switch over immediately to a relatively immature language.
You can use Swift and Objective-c together. There is no issue in it. You need to create a bridging header file.
Please read this
Swift and Objective-C in the Same Project
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