I have a project written in Objective-C and I just added a UIApplication subclass using Swift: RMFApplication.swift (implementation at end of post). However, I am getting this error:
Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Unable to instantiate the
UIApplication subclass instance. No class named RMFApplication is
loaded.'
In my info.plist I correctly specified the name under
NSPrincipalClass, and double checked it.
I read this answer and then looked in my own main.m which says: return UIApplicationMain(argc, argv, nil, NSStringFromClass([RMFAppDelegate class]));.
The docs for UIApplicationMain say that if nil is specified as the thrid value then UIApplication is assumed, but why then does my error message include my custom class name? I have to assume nil means it will read the info.plist value.
Note: Subclassing UIApplication worked well with RMFApplication.h and
RMFApplication.m. The only thing that changed was the renaming of
those files and the addition of a RMFApplication.swift file, which
compiles with no warnings:
import UIKit
class RMFApplication: UIApplication {
override func openURL(url: NSURL) -> Bool
{
println(url.description)
return false;
}
}
I am aware that I can just continue using Objective-C, but I would like to try and migrate to Swift unless the two really don't play well together.
Maybe that's because it uses NSStringFromClass or something, so that in Swift RMFApplication is "mangled" and becomes something like "somePrefix"RMFApplication (or whatever different from just "RMFApplication").
You could try this:
#objc(RMFApplication) class RMFApplication: UIApplication
And then NSStringFromClass will return just "RMFApplication".
Related
I have a Go interface
type GetResponse interface { OnResult(json string) }
I have to subscribe on that event OnResult from ObjC using this interface.
func Subscribe( response GetResponse){ response.OnResult("some json") }
ObjC bind gives me a corresponding protocol and a basic class
#interface GetResponse : NSObject <goSeqRefInterface, GetResponse> {
}
#property(strong, readonly) id _ref;
- (instancetype)initWithRef:(id)ref;
- (void)onResult:(NSString*)json;
#end
So, I need to get this json in my ObjC env. How can I do that?
Subclassing If I subclass this GetResponse or just use it as is and pass to Subscribe routine, it crashes
'go_seq_go_to_refnum on objective-c objects is not permitted'
Category if I create struct on Go side with the protocol support, I can't subclass it but at least it's not crashes:
type GetResponseStruct struct{}
func (GetResponseStruct) OnResult(json string){log.Info("GO RESULT")}
func CreateGetResponse() *GetResponseStruct{ return &GetResponseStruct{}}
I have a solid object without obvious way to hook up my callback. If I make a category and override the onResult routine, it's not called. Just because overriding existing methods of class is not determined behavior according to AppleDoc. Anytime OnResult called from Go, the default implementation invokes and "GO RESULT" appears.
Swizzling I tried to use category and swizzle (replace method's implementation with mine renamed method) but it only works if I call onResult from ObjC env.
Any way to solve my issue? Or I just red the doc not very accurately? Please help me
I ran into a similar issue today. I thought it was a bug in gomobile but it was my misunderstanding of swift/objc after all. https://github.com/golang/go/issues/35003
The TLDR of that bug is that you must subclass the protocol, and not the interface. If you are using swift then you can subclass the GetResponseProtocol:
class MyResponse: GetResponseProtocol
If in objc, then you probably want to directly implement the GetResponse protocol, rather than subclassing the interface.
So, I made a framework in swift and at first I wanted to use a singleton class. I built it and put the .Framework file into a new project to test it. Than I got this error:
'getInstance' is inaccessible due to 'internal' protection level
. I tried looking for anyone with the same problem, but nothing I found worked. It might be because its a framework. After hours of meaningless searching, I gave up on the singleton and I got almost the same error with a normal class.
'mySDK' initializer is inaccessible due to 'private' protection level
I tried making the class public, the initializer public, but nothing seems to change. Anyone experienced any problem like this? I never worked on frameworks before, so maybe its the obj-c header that have to be modified. If you need any more information, please just ask.
Thank you all, in advance.
Edit:
This is the getInstance func. I wrote it only, because the mySDK.myInstance seemed to give the same error.
static let myInstance = mySDK()
public static func getInstance() -> mySDK {
return myInstance
}
I don't know what caused the error, but I managed to fix it by creating a new project, than copy pasting the code from the old to the new.
I found the source of the problem. If I turned off the build active architecture only option in the build settings of the framework, It gave me this error.
You can create a singleton class in a framework like this. Please make the public Class and public static getInstance function.
public class ClassName {
// Singleton instance
private static var instance : ClassName?
/********************* Singleton Instance ************************************/
public static func getInstance() -> ClassName {
if (instance != nil) {
return instance!
}
// Initialize instance.
instance = ClassName()
return instance!
}
}
I have a class defined in Objective-C, whose initializer is -initWithError: (the initializer can fail due to a dependence on an outside resource). I want this to bridge into Swift as init() throws. The regular initializer inherited from NSObject, -init, can be marked unavailable, as I don't want it to be used.
In Objective-C, I have:
#interface Foo : NSObject
- (instancetype _Nullable)initWithError:(NSError **)error;
#end
This works fine in Objective-C, of course.
In Swift, -initWithError gets bridged as init(error: ()) throws. This is presumably because removing withError: from the method name results in init() which conflicts with the inherited plain -init initializer. This can be called from Swift like so:
let foo = try Foo(error: ())
This is strange looking, as the error parameter is void. It would certainly be better if this were imported as init() throws. The obvious solution is to mark -init using NS_UNAVAILABLE in the Objective-C header. Unfortunately, this doesn't work. -initWithError: still gets bridged as init(error: ()), and trying to call try Foo() results in a compiler error saying that init() is unavailable in Swift.
Is there a more elegant solution to this so that try init() just works?
You can rename the function using NS_SWIFT_NAME. In this case:
- (instancetype _Nullable)initWithError:(NSError **)error NS_SWIFT_NAME(init());
That said, this feels like a compiler bug. I'd suggest opening a defect.
Working on a mixed framework. imported inside the Obj-C file but the internal classes are not visible, only the public ones.
The documentation clearly states the internal clasees should be available between Swift and Obj-C:
Importing Swift into Objective-C To import a set of Swift files in the same framework target as your Objective-C code, you don’t
need to import anything into the umbrella header for the framework.
Instead, import the Xcode-generated header file for your Swift code
into any Objective-C .m file you want to use your Swift code from.
Because the generated header for a framework target is part of the
framework’s public interface, only declarations marked with the public
modifier appear in the generated header for a framework target. You
can still use Swift methods and properties that are marked with the
internal modifier from within the Objective-C part of your framework,
as long they are declared within a class that inherits from an
Objective-C class. For more information on access-level modifiers, see
Access Control in The Swift Programming Language (Swift 2).
Code Sample (Create a new project with a framework)
// SwiftObject.swift
public class SwiftObject: NSObject {
public class func doSomething() {}
}
internal class YetAnotherSwiftObject: NSObject {
internal class func doSomething() {}
}
// SomeObject.m file
#implementation SomeObject
- (void)someMethod {
[SwiftObject doSomething];
}
- (void)someOtherMethod {
[YetAnotherSwiftObject doSomething]; // Use of undeclared identifier
}
#end
As indicated in the docs, declarations marked with internal modifier don't appear in the generated header, so the compiler does not know about them and thus complaints. Of course, you could send messages using performSelector approach, but that's not convenient and bug-prone. We just need to help the compiler know that those declarations are there.
First, we need to use #objc attribute variant that allows you to specify name for your symbol in Objective-C:
// SwiftObject.swift
#objc(SWIFTYetAnotherSwiftObject)
internal class YetAnotherSwiftObject: NSObject {
internal class func doSomething() {}
}
And then you just need to create #interface declaration with the methods you want to use in your code - so the compiler will be happy, and also apply SWIFT_CLASS macro with the symbol name you've specified earlier - so the linker would pick the actual implementation:
// SomeObject.m file
SWIFT_CLASS("SWIFTYetAnotherSwiftObject")
#interface YetAnotherSwiftObject : NSObject
+ (void)doSomething;
#end
#implementation SomeObject
- (void)someOtherMethod {
[YetAnotherSwiftObject doSomething]; // Should work now !!!
}
#end
I've used the interface declaration in .m file just for clarity, the better option would be to combine such declarations in .h file, and include it.
By declaring methods in that interface we're making a promise to compiler, and it won't complain if you'll put there a method that does not exist (or with wrong signature, etc.) Obviously, you'll crash in runtime in that case - so be cautious.
For me it just worked by checking: "Allow app extension API only". You find it by going to the project setting, select your target and then it is in the General tab under Deployment Info.
Can someone explain to me, why this does solve the problem?
While the above solution works (https://stackoverflow.com/a/33159964/5945317), it seems overly complicated and unintuitive:
Complicated, because it seems to add more things than necessary – I will provide a smoother solution below.
Unintuitive, because the objc macro SWIFT_CLASS resolves to SWIFT_RUNTIME_NAME, and the provided value is not actually the runtime name – nor is the objc class name in the header matching the Swift attribute param in #objc. Still, surprisingly, the solution works – but to me it is not clear why.
Here is what we have tested in our own project, and believe to be the better solution (using the example above):
// YetAnotherSwiftObject.swift
#objc(OBJCPREFIXYetAnotherSwiftObject)
internal class YetAnotherSwiftObject: NSObject {
#objc internal class func doSomething() {}
}
// OBJCPREFIXYetAnotherSwiftObject.h
#interface OBJCPREFIXYetAnotherSwiftObject : NSObject
+ (void)doSomething;
#end
That's it. The interface looks like a regular objc interface. This gives the added benefit that you can include it in other header files (which you cannot do if you use the SWIFT_CLASS macro, as it comes from the autogenerated Swift header file, which in turn you cannot include in an objc header, due to circular dependency).
On the Swift side, the only thing relevant is that you provide the class with the proper objc name. Mind that I only used the name prefix for language consistency – you can even just use YetAnotherSwiftObject everywhere (i.e., in the objc header and in the #objc attribute in Swift – but you need to keep this attribute with explicit naming in any case, and need to keep it consistent with the class name in the header).
This also makes your life easier if you're in the process of converting your objc framework step by step to Swift. You just keep the objc header as before, and now provide the implementation in Swift.
Methods and properties that are marked with the internal modifier and declared within a class that inherits from an Objective-C class are accessible to the Objective-C runtime.
so let's make use of that:
class MyInternalClass: NSObject {
#objc var internalProperty = 42
}
#interface MyPublicClass()
#end
#implementation MyPublicClass
+ (void) printValue {
Class myInternalClass = NSClassFromString(#"MyPackageNameIfAny.MyInternalClass");
id myInternalClassInstance = [myInternalClass new];
int value = [myInternalClassInstance performSelector:#selector(internalProperty)];
NSLog(#"Value is %d ", value); // "value is 42"
}
#end
Using the SWIFT_CLASS macro and #objc class attribute could easily lead to errors when archiving. This approach is safer.
I have a crash in my Swift project with MagicalRecord - CoreData library : https://github.com/magicalpanda/MagicalRecord
First, I setup MagicalRecord OK in AppDelegate.swift:
MagicalRecord.setupCoreDataStack() //-> This is OK. Don't crash
But, when I want to create a "Contact" entity instance I got a Crash.
My code is the next:
var context = NSManagedObjectContext.MR_contextForCurrentThread() // -> This is OK. Don't crash
var contact = Contact.MR_createInContext(context) // -> CRASH
All compile OK but when the App is running I get the next crash:
Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: '+entityForName: could not locate an entity named 'MyProject.Contact' in this model.' *** First throw call stack:
(0x27861f77 0x34870c77 0x27590c73 0x9b93d 0x74f28 0x75438 0x2aea6e33 0x2b09acef 0x2b09d19d 0x2b0a79f9 0x2b09ba5b 0x2e106141 0x2782881d 0x27827ae1 0x2782627f 0x27773da1 0x27773bb3 0x2aea0ae7 0x2ae9bc41 0x75ab0 0x75aec 0x34e10aaf)
libc++abi.dylib: terminating with uncaught exception of type NSException
MyProject key is the $(PRODUCT_NAME), how I can fix this?
Kind regards
There is a simple solution to this issue. Just add #objc(ClassName) before the swift NSManagedObject subclass. This allows the Objc side know the right name for the class. Otherwise it will include the module name which is bad in this case because it won't match what you have in your Core Data model. Here's and example from one of my swift projects...
#objc(Plant) public class Plant: NSManagedObject
It seems like MagicalRecord automatically computes the entity name, and does this the wrong way. You can possibly fix this by adding the following code to your Contact class:
class func entityName() -> String {
return "Contact"
}
In Swift, you likely need to set the class for your entity to MyProject.Contact for it to be found automatically though the model. In the Entity inspector on the right of the Entity modeler, you can change the class name there.
The solution of Guido Hendriks with an extension to support all managed objects:
extension NSManagedObject {
class func entityName() -> String {
return NSStringFromClass(self).componentsSeparatedByString(".").last!
}
}
Thank you for the answers. I Think that Guido Hendriks's is a good answer. I tried casademora answer but I didn't got the App work.
Finally I have changed the CoreData classes language (Contact Class) from Swift to Objective-C and now the MagicalRecord library works fine!
Thank you!
I had to deal with the same problem and took me a while to figure out how to...
Thanks #casademora I created the classes as Obj-C ones and imported the headers in bridging-header of my swift project.
Select your .xcdatamodeld file
Editor
Create NSManagedObject Subclass
Select your data model and entities
Save the file as an Objective-C class
Here you go with a nice picture:
And in the prefix header file:
#ifndef DBSwiftTest_Bridging_Header_h
#define DBSwiftTest_Bridging_Header_h
#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>
#import "DKDBManager.h" // My database manager
#import "Runner.h" // My model in this example
#endif
You can create your entity classes in objective-c and exposing them via bridging header to swift. That way crash dissappears
I have the same issue. Here is what i did to solve it:
Step 1: As Guido Hendriks mentioned in his answer
It seems like MagicalRecord automatically computes the entity name, and does this the wrong way. You can possibly fix this by adding the following code to your Contact class"
class func entityName() -> String {
return "Contact"
}
Step 2: In your DataModel, change the Class of the Entity from Contact to ProjectName.Contact