I need to extend the functionality of a library Pod written in Objective C (the rest of the project is in Swift). I created the MyClass+Category .h and .m files (as a Category), with the pod selected as target, but I get a file not found error in the header at:
#import <MyLib/MyLib.h>
How do I get the category's header to find the original class?
An alternative would be to write the extension in Swift, are there any gotchas there I should be aware of?
Also grateful for any better ways there might be.
Adding a Bridging Header in Your Project. then import your category in BridgingHeader class. you easily access your category.
how to add header file please see this link.
https://stackoverflow.com/a/39615171/8687925
Related
In my Swift Project, I added a new cocoa Objective-C class (UIViewController), Xcode prompted me whether I want it to automatically generate an Objective-C bridging header file.
I am a bit confused because the generated file is ProductModuleName-Bridging-Header.h while, as per Apple documentation, I was waiting to get a ProductModuleName-Swift.h instead (In order to import Swift into Objective-C).
The ProductModuleName-Bridging-Header.h is mandatory in order to be able to import Objective-C from Swift, and not the inverse.
Any clarification on this?
Thanks
The behavior you describe is exactly correct. You're adding Obj-C to your Swift project, therefore Xcode offers to create a -Bridging-Header.h file which allows that imported Obj-C to be used in your Swift code. This is described in the documentation you linked under "Importing Objective-C into Swift".
Unlike the bridging header, the -Swift.h file doesn't appear in your file hierachy, and is not something you see or edit. It's generated and managed entirely by Xcode during the build process. You simply import into .m files when needed.
Note: I know How to call Objective-C code from Swift, but I don't know below,
I want to use this EsptouchForIOS's Demo in my project. The demo is write in OC, it has a storyboard and controller. I want to know how to integrate the demo in my swift project, and use that storyboard and it's controller in my swift project.
I'll start writing from the very beginning. Suppose you have a project in Objective-C and now you want to continue your project's development in Swift. Follow the below guidelines: (This intends to your specific needs)
First choose to add a new file from File->New->File. In this process select your language as Swift. In the final step here, you will be prompted to Create Bridging Header. Select that:
Now build your project once (⌘+B). You may get an error like this:
Change your target's minimum deployment to the version that Swift supports. (Example in the below screenshot)
To use Objective-C resources in Swift files:
Now that you've got one ProjectName-Bridging-Header.h file in your project. If you want to use any Objective-C class in your Swift files, you just include the header file of that class in this bridging header file. Like in this project, you have ESP_NetUtil and ESPViewController class and their header files too. You want to expose them to Swift and use them later in Swift code. So import them in this bridging header file:
Build once again. Now you can go to your Swift file. And use the Objective-C classes as like you use any resource in swift. See:
N.B: You must expose all the class headers (that you're intending to use later in Swift) in that bridging header file
To use Swift resources in Objective-C files:
Now you may wonder, I've successfully used Objective-C resources in Swift. What about the opposite? Yes! You can do the opposite too. Find your Target->Build Settings->Swift Compiler - General->Objective-C Generated Interface Header Name. This is the header file you will be using inside your Objective-C classes for any Swift to Objective-C interoperability. To know more check here.
Now inside any of your Objective-C class, import that interface header and use Swift resources in Objective-C code:
You will get more understanding from the official apple documentation.
You can checkout the worked out version of your linked project here with Objective-C-Swift interoperability.
So according to your question, you have added an objective C bridge in your swift project using How to call Objective-C code from Swift.
Now, import all headers (.h) files of your objective-c source code (demo project) that you want to direct use in swift file.
For example, your demo project has EsptouchForIOS following header (file with extension .h) files in project source code.
ESPAppDelegate.h, ESPDataCode.h, ESPTouchDelegate.h
import a header file in your bridge, which you want to use in your swift code. Suppose in your swift code you want touch delegate ESPTouchDelegate then write,
#import "ESPTouchDelegate.h"
Here is snapshot of your demo integration in my Test Swift project with bridge
and import statements.
Now, there is function/method in an objective C file getValue
which is used/accessed in swift project/file.
Similarly, you can import as many files (source headers) as you want in bridge and use the same files (source code) in swift.
I have never tried to use objective-c from swift project. But I normally used swift classes from my objective-c project. I usually follow this instructions https://developer.apple.com/library/content/documentation/Swift/Conceptual/BuildingCocoaApps/MixandMatch.html from apple developer website.
I have an objective-c class that uses swift classes. It all works fine.
I wanted to import the objective-c class into a swift class, so I added its header file to the bridging header. All the sudden I got an error the Projectname_swift.h file is not found.
Any ideas how to resolve this issue?
Is it actually possible?
a circular reference has been created, making it so the Swift code is unable to compile (which leads to the canary error stating that the _Swift.h file is not found).
i have provided a more in depth answer to a similar questions here and here.
long story short, the documentation explicitly says not to this:
To avoid cyclical references, don’t import Swift code into an Objective-C header (.h) file. Instead, you can forward declare a Swift class or protocol to reference it in an Objective-C interface.
Forward declarations of Swift classes and protocols can only be used as types for method and property declarations.
in order to make your code compile again you will need to remove the #import "Projectname_Swift.h" line from the offending Objective-C header. ideally you can simply move the import statement into your .m file, however if you need to publicly expose the Swift class in your ObjC header, then you must forward declare it using #class SomeSwiftClass;.
Let the Xcode build the bridge file from Objective-C to Swift.
Create a temporary directory elsewhere. In there, you create a dummy Xcode Swift project, give the project name the same as your existing Current Project Name.
Then add new file, Objective-C (.m file). The XCode will prompt you to create a bridge header file, click on the create bridge file (the right most button).
Now you locate the header file location in Finder. Then drag into your Current Project of Interest, don't forget to checked the copy file if necessary option. Add necessary #import '.....' in the header file.
You should be good. If everything works fine, delete the dummy project.
Clean derived data. and then #import "ProjectName-Swift.h" in your objective c files.
Go to
Build Settings->Objective-C Generated Interface Header Name
and set the value to YourModule-Swift.h (this is usually already set, this is the filename you need to import on .m file #import "YourModule-Swift.h"
Go to Build Settings and search for "Defines Module", set both values to YES
Create a class in swift with prefix of #objc for example
#objc class mySwiftClass{...}
Build the project again
it will be better if you use error syntax or screen shot. you can simply try this
1. Goto your project on top of right navigation
2. select build settings from middle pain.
3. search for Objective-C bridging header
4. just below this you will find "Generated interface HeaderName"
5. add correct address of your swift file
6. clean and build the project.
I am confused when working with Xamarin obj-c bindings, Lets say if I am having a single .h file then its just an happy path when creating binding. But when a .h file is referenced with another .h in it as an import statement. How to deal with the bindings.
If I am having AB.h file which has A.h referred in it, what is the way to generate bindings for this. And If I am having a .xib file in obj-c project then how to deal with that.
Example Sake I am using this project for conversion.
https://github.com/hightower/HTHorizontalSelectionList/tree/master/Source
Have you looked at the Objective Sharpie, it will automatically identify the dependency and help you get started with creating iOS bindings
I added some Obj-C code (the excellent Expressions) to my Swift project using Xcode's Add files... but it did not ask me if I wanted to make a bridging header. So I made one myself in the Obj-C code's group, edited it to #import the single header I needed, and made sure that file was referenced in the Swift Compiler in Build Settings. I then looked through the Obj-C code and made sure the .m files were in the target - they were, and they're listed in Compile Sources.
The header in question contains this:
#interface NSNumber (Expression)
+ (NSNumber *)numberByParsingExpression:(NSString *)expression;
+ (NSNumber *)numberByParsingExpression:(NSString *)expression withVariables:(NSDictionary *)varDictionary;
#end
Now I am trying to call this code using the same basic syntax as this post:
let result = NSNumber.numberByParsingExpression(f.1)
along with several variations on the theme. But it won't compile, "Type 'NSNumber' has no member 'numberByParsingExpression'".
Did I miss a step here?
According to https://developer.apple.com/library/ios/documentation/Swift/Conceptual/BuildingCocoaApps/MixandMatch.html
You can create a bridging header yourself by choosing File > New >
File > (iOS, watchOS, tvOS, or OS X) > Source > Header File.
You’ll need to edit the bridging header file to expose your
Objective-C code to your Swift code.
In your Objective-C bridging header file, import every Objective-C
header you want to expose to Swift. For example:
In Build Settings, in Swift Compiler - Code Generation, make sure the
Objective-C Bridging Header build setting under has a path to the
bridging header file. The path should be relative to your project,
similar to the way your Info.plist path is specified in Build
Settings. In most cases, you should not need to modify this setting.
Any public Objective-C headers listed in this bridging header file
will be visible to Swift. The Objective-C functionality will be
available in any Swift file within that target automatically, without
any import statements. Use your custom Objective-C code with the same
Swift syntax you use with system classes.
If you already did this correctly, and it still isn't working, try deleting the projects derived data, and clean building your project.
Ok, this turns out to be an Xcode peccadillo.
When you create the header file within the group, it actually places it physically in the source folder. So in my case the header was created in /project/subproject/.h although it appeared within Xcode to be part of the base folder, /project/.h.
So in fact there were two headers, one in the right place with nothing in it, and another in the wrong place that was the one that was being edited within Xcode. So you have to look at the file inspector to make sure it placed the bridging header in the right place!