Objective-C lightweight generics won't compile - ios

Having just upgraded to Xcode 12/iOS 14, the Intents framework is trying to compile code like this in various headers:
#interface INObjectSection<ObjectType> : NSObject <NSCopying, NSSecureCoding>
But the compiler seems to have no idea that ObjectType is the generic placeholder:
No type or protocol named 'ObjectType'
Nobody else is complaining about this, so I'm guessing I have some setting in this very old project that is preventing Objective-C generics from compiling, but I can't find anything.

For some reason the #import syntax no longer works. I replaced
#import <Intents/Intents.h>
with
#import Intents;
and now it compiles.

Related

Swift framework - Use Swift class reference in Objective-C class

I am creating Swift framework in which I have to use Objective-C class. So I went through this link. This is the public header of my framework :
#import <UIKit/UIKit.h>
//! Project version number for Test.
FOUNDATION_EXPORT double TestVersionNumber;
//! Project version string for Test.
FOUNDATION_EXPORT const unsigned char TestVersionString[];
// In this header, you should import all the public headers of your framework using statements like #import <Test/PublicHeader.h>
#import <arpa/inet.h>
#import <ifaddrs.h>
#import <netdb.h>
#import <sys/socket.h>
#import <MyTest/MPAppDelegateProxy.h>
Now in class MPAppDelegateProxy, I have to use a Swift class which I have created. This is :
#import "MPAppDelegateProxy.h"
#import "MyTest.h"
#implementation MPAppDelegateProxy
+ (void)proxyAppDelegate {
[MPGlobal MPLog:#"App delegate not set, unable to perform automatic setup." file:#"MPAppDelegateProxy.m" function:#"proxyAppDelegate" line:32];
// rest of code
}
MPGlobal is one of my Swift class. But I am getting :
Use of undeclared identifier 'MPGlobal'
Note : I have added #objC before MPGlobal.
You need to import <Target>-Swift.h file.
This is known as Objective-C Generated Interface Header Name.
You can find it in your Target's build settings.
This file is auto generated by compiler and it needs to be imported in Objective-C files.
change the SWIFT_OBJC_INTERFACE_HEADER_NAME build setting and making it the same across different targets. To do so change the instruction that generates this property from $(SWIFT_MODULE_NAME)-Swift.h to $(PROJECT_NAME)-Swift.h as explained here
After doing this Clean Build Folder by pressing Alt and going into Product menu. Since name of header is shared among targets now it can be imported once in the .m ObjectiveC file and all targets can benefit from Swift classes.
If after building it still shows the error, ensure that the header can be reached from XCode by Cmd clicking on its name. It should open a file that contains code similar to this:
SWIFT_CLASS("_TtC27ProjectName_Summary11MyClass")
#interface MyClass : NSObject
- (nonnull instancetype)init OBJC_DESIGNATED_INITIALIZER;
#end
If need to ensure that those headers are being generated open a terminal and use this command
find ~/Library/Developer/Xcode/DerivedData -name "*Swift.h"
You should see one header for each target
Another issue that happened to me after those changes is that it started giving errors on ObjectiveC code that I didn't touch. The problem was due to the position of the import, as reported here:
Exactly where at the top of a .m file you #import the hidden bridging
header can make a difference. The usual sign of trouble is that you
get an “Unknown type name” compile error, where the unknown type is a
class declared in Objective-C. The solution is to #import the .h file
containing the declaration for the unknown type in your Objective-C
files as well, before you #import the hidden bridging header. Having
to do this can be an annoyance, especially if the Objective-C file in
question has no need to know about this class, but it resolves the
issue and allows compilation to proceed.
At the very end the code compiles and runs on device and simulator!
Original answer
Also you can try this,
You needed to import the -Swift.h for for both the framework and the app target
For Example :
#import <UIKit/UIKit.h>
#import <AVFoundation/AVFoundation.h>
#import <Foundation/Foundation.h>
#import "XLPagerTabStrip-Swift.h"
#import "RealmSwift-Swift.h"
...... // Add all frameworks, subclasses, and dependance ios frameworks
#import "MyProject-Swift.h"
You can read this article How to import file header and check paths

Project-Swift.h file not found

I have a new Swift project with a few files, I've needed to add some Objc code.
In Build Settings, my Objective-C Generated Interface Header Name is MyProject-Swift.h
Product Module Name and Product Name are both MyProject.
My Objective-C Bridging Header is MyProject/MyProject-Bridging-Header.h
The contents of my Bridging Header are:
#ifndef MyProject_Bridging_Header_h
#define MyProject_Bridging_Header_h
#import "Blakey.h"
#endif
Blakey.h is pretty simple:
#import Foundation;
#import "MyProject-Swift.h"
#class KeyPair;
#interface Blakey: NSObject
- (void)createKeyPairForSeed:(NSString *)seed;
#end
And Blakey.m
#import <Foundation/Foundation.h>
#import "Blakey.h"
#implementation Blakey
- (void)createKeyPairForSeed:(NSString *)seed;
{
}
#end
(side note: I'm aware my function returns a void, that will be changed later once this issue is fixed so it returns an actual value)
Why is Xcode throwing an error at the #import "MyProject-Swift.h" in Blakey.h?
Project-Swift.h is a file auto generated by Xcode on successful compilation of the project. Catch here is the word successful compilation If your project has any compilation error Project-Swift.h file will not be generated. So in a way it becomes a deadlock. Bestway comment out all the lines that have compilation error and then manage to get it compile without any errors. Only after that Project-Swift.h will be generated.
Additional information, Once the Project-Swift.h file is generated if you open it and if you happened to see that your swift class is not imported there thats because Project-Swift.h imports only the classes that extends from NSObject So plain Swift classes will not be imported.
ISSUE:
You need to import Project-Swift.h in .m file and not .h file. So modify your Blakey as
#import <Foundation/Foundation.h>
#import "Blakey.h"
#import "MyProject-Swift.h"
#implementation Blakey
- (void)createKeyPairForSeed:(NSString *)seed;
{
}
Finally remove #import "MyProject-Swift.h" from Blakey.h
#import Foundation;
#class KeyPair;
#interface Blakey: NSObject
- (void)createKeyPairForSeed:(NSString *)seed;
#end
I had similar issue and almost ended up spending a whole day trying to figure out what wrong with my app.
So following the solution that's helped me :
Clear derived data
Create a class in swift with prefix of #objc for example #objc class mySwiftClass{...}
Build the project again
Et voila.. Should work now.
Why to add #objc?
this #objc prefix, tells the compiler to generate to your swift class a header file. it will add it to the "MyModule-Swift.h" file
I realize this is an old thread, but I had similar issues after adding a new target to a project. I solved it by adding a preprocessor macro (Build Settings -> Apple Clang - Preprocessing) only in said target and then importing the Swift.h file conditionally, like this:
#if DEV_VERSION
#import "Project_DEV-Swift.h"
#else
#import "Project-Swift.h"
#endif
My main target is called Project and the new target is Project DEV (the space is replaced with an underscore in the import), and the preprocessor macro is called DEV_VERSION.
After doing this, both targets build just fine.
<product_name>-Swift.h file not found
It is a kind of bridge(adapter) between Swift and Objective-C. This file contains Swift's API for Objective-C which was marked [#objc and #objcMembers].
You can work with types declared in Swift from within the Objective-C code in your project by importing an Xcode-generated header file.
The header's name is generated from a <product_name>-Swift.h
[Mixing Objective-C and Swift ]
I had a similar issue whereby it would have this issue for anything other than live.
I resolved the issue by hardcoding "Product module name" & "Product name" to my project name. This avoids the need to have preprocessor logic in every file that includes swift code as demonstrated in Pauli Kettunen's solution.

Xcode 9 Beta 2 libxml error

When I build my project with beta 1 it works just fine, but in beta 2 it does not work. In this build I get all sort of errors with libxml I think. For example:
* tree.h:81:3: Unsupported: typedef changes linkage of anonymous type, but linkage was
already computed
* tree.h:346:8: Redefinition of '_xmlElement'
I think this is because somehow libxml is include twice in my project or something. If I change all the #include/imports with the #import xml2 statements it compiles again. The include are guarded by defines.
I want to know if this is the correct solution and why this is needed or is this a bug?
To reproduce problem:
I'm using a wrapper around libxml so I can use objc. When I strip all code the problem can be reproduced with these files/classes:
// DDXMLNode.h
#import <libxml/tree.h>
//#import xml2.tree;
#import Foundation;
#import ObjectiveC.runtime;
#interface DDXMLNode : NSObject<NSCopying>
#end
// DDXMLNode.m
#import "DDXMLNode.h"
#implementation DDXMLNode
#end
I added libxml2 through build phases and just add libxml2.tbd.
As Calimari328 said in the comments this is fixed in xCode beta 3.

Private method compilation error

I have imported a library, but during the compilation Xcode shows an error in two .h files of this framework:
#interface BxAbstractDataSet (private)
#interface BxQueueDataCommand (private)
after the first bracket Expected ')'
I thing that there is some problem with the build LLVM settings, but can't solve the issue - any help?

Unknown type name when trying to include a library

I'm trying to use Novocaine in an iPhone application I'm building. I can't figure out how to get around this error I'm getting:
Unknown type name 'RingBuffer'
Here's my file structure:
...with those files under Novocaine being the ones pulled from the Github repo for Novocaine. Here's my header file for DDViewController.
#import <UIKit/UIKit.h>
#import <QuartzCore/QuartzCore.h>
#import "UICoordButton.h"
#import "Novocaine.h"
#import "RingBuffer.h"
#import "AudioFileReader.h"
#import "AudioFileWriter.h"
#interface DDViewController : UIViewController
{
RingBuffer *ringBuffer;
Novocaine *audioManager;
AudioFileReader *fileReader;
AudioFileWriter *fileWriter;
}
- (IBAction)changeColor:(id)sender;
- (IBAction)changeColor2:(id)sender;
#end
I've tried a solution that I found on another question, which suggests that this should work:
#class RingBuffer;
#interface DDViewController : UIViewController
{
...
But that just gives me Redefinition of 'RingBuffer' as a different kind of symbol.
How can I fix this problem and use RingBuffer?
RingBuffer is a C++ class. I recommend you change the extension of your Objective-C files from .m to .mm which will make them Objective-C++
Found the answer (or I guess a combination of answers):
Follow coryalder's advice for setting the compiler default to Objective-C++ as described here.
Also, change all .m files to .mm files, and finally add -fno-objc-arc compiler flags to all the .mm files -- which is described in detail here.

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