I'm trying to continue with Swift in an existing project I had started in Objective-C. I followed the Apple documentation and I managed to access a Swift class from an Objective-C file, via including the "ProductModuleName-Swift.h" header in my Obj-C file.
At this point here's my code:
#include "Pianoconcert_App-Swift.h"
#interface ModelsVC ()
#end
#implementation ModelsVC
// And all that kind of stuff
// ...
-(IBAction)comanda:(UIButton *)sender {
ComandaTableVC *controller = (ComandaTableVC *)self.tabBarController.viewControllers[2];
// Here goes the problematic code
[self.tabBarController setSelectedIndex:2];
}
This piece of code has no problems. But now I just want to set one of the variables in the Swift class like this: controller.selectedModel = sender.tag, but Xcode just tells me the variable does not exist.
Here's an extract of my Swift class:
import UIKit
class ComandaTableVC: UITableViewController, UIPickerViewDataSource, UIPickerViewDelegate {
// Declaration of some constants and variables
// And here goes the one
var selectedModel: Int = 0
// And a bunch more of variables and functions
// ...
}
I don't know what I'm doing wrong. The class seems fully included and, actually, I can access that variable and all the others if I use the class from another Swift file, like this:
var controller: ComandaTableVC = self.tabBarController.viewControllers[2] as ComandaTableVC
controller.selectedModel = 2
It's been resolved finally, but I can't explain how.
Suddenly the compiler threw a build error telling me that the file Pianoconcert_App-Swift.h could not be found.
I changed it for PianoconcertApp-Swift.h, deleting the underscore that replaced the blank space, and now I can access all the variables and constants correctly.
Related
I am a newbie for objc. I have written a class exposing it to the JS side using swift. The content in that file looks like as follows,
import Foundation
#objc(AppLinkModule)
class AppLinkModule: NSObject{
#objc
static var appLink: String?
#objc
func setLink(link: String){
AppLinkModule.appLink = link;
}
#objc
func getLink(_ resolve: RCTPromiseResolveBlock, rejecter reject: RCTPromiseRejectBlock) -> Void {
resolve(AppLinkModule.appLink);
AppLinkModule.appLink = nil;
}
}
The AppLinkModule.m file is as follows,
#import "React/RCTBridgeModule.h"
#interface RCT_EXTERN_MODULE(AppLinkModule, NSObject)
RCT_EXTERN_METHOD(getLink)
#end
What I actually want is to call the setLink method from the AppDelegate.m file or else directly set to the static variable appLink. Some instructions to achieve this will be greatly appreciated.
This looks fine.
If you want to call getLink() from your App Delegate, you'll need to import the Auto-generated Swift Bridging Header File that Xcode creates when you compile your code. This will allow the Objective-c AppDelegate.m file to find your exposed swift code.
#import <ProjectName-Swift.h> will allow your Swift to be exposed to the AppDelegate, and you already have marked the class and functions #objc so they will be visible.
Then you just need to either create a singleton or shared instance of your AppLinkModule (React Native Modules are all run statically) or you need to instantiate your module class.
Once you've done so, you can call this function in the AppDelegate like so:
[[[AppLinkModule ] shared ] getLink];
All tutorials for using swift code in a primarily objective-c app goes through this process mentioned in this Apple document https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/BuildingCocoaApps/MixandMatch.html
But this methodology of importing a xyzProjectName-swift.h file and then using
MySwiftClass *swiftObject = [[MySwiftClass alloc] init];
[swiftObject swiftMethod];
required me to create an instance of that swift class. Is it possible to directly access the class itself like [MySwiftClass swiftMethod];
I have not been able to do this until now. Do I have to change my swift code in a certain way to achieve this?
Just tried the following:
class MySwiftClass: NSObject {
static func swiftMethod() -> String {
return "hello"
}
}
And in Objective-C:
NSLog(#"Received from Swift: %#", [MySwiftClass swiftMethod]);
Works for me - are you sure your swiftMethod is static, and not private? You could also try adding #objc in front of the static func – if nothing else, at least it might warn you if there is a reason it can't be accessed from Objective-C.
I'm working on building a new Swift app roughly based off an old Obj-c app. I'm currently working on the delegates
Here is what my obj-c code looked like in the .h file
#interface MyAppViewController : CustomViewController
#property (nonatomic, weak) id<MyAppViewControllerDelegate> delegate;
#end
#protocol MyAppViewControllerDelegate <NSObject>
- (void)myAppViewController:(MyAppViewController *)controller loggedInStudent: (MYStudent *)student;
- (void)myAppViewControllerWantsSignUp:(MyAppViewController *)controller;
#end
In SWIFT I did:
class MyAppViewController: CustomViewController {
var delegate: MyAppViewControllerDelegate?
protocol MyAppViewControllerDelegate{
func myAppViewController(controller: MyAppViewController, loggedInStudent: MYStudent)
func myAppViewControllerWantsSignUp(controller: MyAppViewController)
I've done a lot of reading and study on this, so I thought I was doing it basically right (totally new to swift though... so)
I'm getting this error though, "Declaration is only valid in file scope" on the protocol MyAppViewControllerDelegate {
I assumed this had something to do with declaring it within the class, so I moved it out, only now my code within the class doesn't recognize the delegate variable I declared..
Any ideas?
Should be this:
protocol MyAppViewControllerDelegate {
func myAppViewController(controller: MyAppViewController, loggedInStudent: MYStudent)
func myAppViewControllerWantsSignUp(controller: MyAppViewController)
}
class MyAppViewController: CustomViewController {
var delegate: MyAppViewControllerDelegate?
}
Although, if you're following a common pattern where the object that owns MyAppViewController is also its delegate, this may cause memory issues. You can use class typing to allow weak delegation like so:
protocol MyAppViewControllerDelegate : class {
func myAppViewController(controller: MyAppViewController, loggedInStudent: MYStudent)
func myAppViewControllerWantsSignUp(controller: MyAppViewController)
}
class MyAppViewController: CustomViewController {
weak var delegate: MyAppViewControllerDelegate?
}
This is slightly limiting because it requires you to use a class for your delegate, but it will help avoid retain cycles :)
From what I see in your source code is that you've declared your protocol inside of your class.
Just declare the protocol outside of the class declaration and you'll be fine.
Update:
The default access level is set to internal which is defined as
Internal access enables entities to be used within any source file from their defining module, >but not in any source file outside of that module. You typically use internal access when >defining an app’s or a framework’s internal structure.
In contrast to Objective-C or C you don't need a forward declaration if the implementation haven't happened before the usage.
Source: The Swift Programming Language, Access Control
I have problems to understand, why some member functions from an imported (and complicated) set of Objective-C interface are not available in Swift.
I have a Bridging-Header File:
#import "EvernoteSDK.h"
and I can't use some member functions in my ViewController
let userStore = EvernoteUserStore()
userStore.initWithSession(session)
initWithSession is not available for the swift code, but why?
The objective-C header shows:
#interface EvernoteUserStore : ENAPI
+ (instancetype)userStore;
- (id)initWithSession:(EvernoteSession *)session;
If I could view the exposed Objective-C header, I may understand, how the mangling works
In Swift the initializer call is combined with the constructor. In other words, Objective-C's
EvernoteUserStore *userStore = [[EvernoteUserStore alloc] initWithSession:session];
becomes
let userStore = EvernoteUserStore(session:session);
The tool recognizes the initWithSomething: name of Objective-C, and converts it to
init(something something : SomeType)
In case of EvernoteUserStore the corresponding init method looks like this:
init(session session: EvernoteSession!)
I'm stuck trying to combine openGL-es (xcode openGL game template with the ogles2tools library from powervr 3.0 sdk. My problem is the line of code where I load the effect file:
/*
Load the effect.
We pass 'this' as an argument as we wish to receive callbacks as the PFX is loaded.
This is optional and supplying NULL implies that the developer will take care
of all texture loading and binding to to the Effect instead.
*/
if(m_pEffect->Load(*m_pEffectParser, "Effect", c_szPfxFile, NULL, uiUnknownUniforms, &error) != PVR_SUCCESS)
{
NSLog(#"%s",error.c_str());
return;
}
I'm supposed to pass a "this" pointer so I can receive the callbacks. The delegate method I need to implement is:
EPVRTError OGLES2IntroducingPFX::PVRTPFXOnLoadTexture(const CPVRTStringHash& TextureName, GLuint& uiHandle, unsigned int& uiFlags)
{
/*
This is an optional callback function for PVRTPFXEffect and can be used to automate
the texture loading process.
If multiple effects are to be loaded and they share textures it would be
prudent to have a caching system in place so texture memory is not wasted.
Please see OGLES2MagicLantern for an example of this.
*/
if(PVRTTextureLoadFromPVR(TextureName.String().c_str(), &uiHandle) != PVR_SUCCESS)
return PVR_FAIL;
return PVR_SUCCESS;
}
I guess the big issue for me is how do I go about providing a cpp delegate method in objective-c? I did some reading on this issue, but it seemed what I was reading was going the other way. That is, an objective-c delegate in cpp. It's pretty confusing, but here's my thought...
I create a cpp class the implements the method I need. I add that to my viewController class and pass the pointer to this cpp class in the m_pEffect->Load call. Does this seem correct?
Thanks.
P.S. Sorry if my code formatting is bad. I'm still learning.
Edit: Here's the example I found regarding mixing the objective-c and cpp. It seems really similar to what I want to do.
Update: Here's some additional info (requested by user1118321)
The CPP class which needs a delegate is CPVRTPFXEffect (PVRTPFXParserAPI.h - from powerVR SDK 3.0). I would add a link, but I'm not sure if this is allowed. Here's a link to the class header, but this version (and others on the web) did not include the pDelegate attribute for the load method. I'm assuming they are examples of a previous version. Let me know if it's okay to post this class file and I will do so.
I found a good example of what I think I'm supposed to do from reading this thread. So here's what I have so far:
My CPP delegate class...
class myCppDelegate : public PVRTPFXEffectDelegate {
public:
myCppDelegate() {};
EPVRTError PVRTPFXOnLoadTexture(const CPVRTStringHash& TextureName, GLuint& uiHandle, unsigned int& uiFlags) {
return PVR_FAIL;
};
};
My Obj-C wrapper class (just modified from the example link above)...
struct RNWrapOpaque;
#interface RNWrap : NSObject {
struct RNWrapOpaque *_cpp;
}
- (id)init;
#end
implementation...
#import "RNWrap.h"
#import "Wrap.h"
#interface RNWrap ()
#property (nonatomic, readwrite, assign) RNWrapOpaque *cpp;
#end
#implementation RNWrap
#synthesize cpp = _cpp;
struct RNWrapOpaque
{
public:
RNWrapOpaque() : wrap() {};
myCppDelegate wrap;
};
- (id)init
{
self = [super init];
if (self != nil)
{
self.cpp = new RNWrapOpaque();
}
return self;
}
- (void)dealloc
{
delete _cpp;
_cpp = NULL;
// [super dealloc];
}
#end
Basically I am able to compile the code and debug, but when the the CPVRTPFEffect class makes this call:
if(pDelegate->PVRTPFXOnLoadTexture(pTexDesc->FileName, uiHandle, uiFlags) != PVR_SUCCESS)
I get EXC_BAD_ACCESS. I'm assuming it's not finding my callback method, because I set a breakpoint and the line never gets called.
Here's my updated code which calls CPVRTPFXEffect::Load using a bridge command for the delegate parameter.
if(m_pEffect->Load(*m_pEffectParser, "Effect", c_szPfxFile,(__bridge myCppDelegate*)opaqueCppWrap, uiUnknownUniforms, &error) != PVR_SUCCESS)
Thanks for your help!
Update 2: The project uses ARC. Here's what my viewController interface looks like:
#interface ViewController : GLKViewController {
...
RNWrap* opaqueCppWrap;
...
}
#property (strong) RNWrap *opaqueCppWrap;
Adding the #property didn't help with the EXC_BAD_ACCESS. I'm not sure how to "see" the value of pDelegate when I'm tracing the CPP code. Xcode doesn't reveal anything when I hover over the variable.
I added the following line of code to the CPVRTPFXEffect::Load method (just prior to the line where it crashes):
*pReturnError += PVRTStringFromFormattedStr("Here is your class typeid: %s.\n", typeid(pDelegate).name());
return PVR_FAIL;
This is what displayed in the debug output window:
Here is your class typeid: P21PVRTPFXEffectDelegate.
I'm not sure what the "P21" means (if anything), but it looks like I'm close to getting this working. I dunno, maybe this is as close as it gets. Still crashing and not finding my method.
First, you may want to look at the last article in the series on wrapping C++. Most of it has gotten much simpler in the latest versions of clang. You probably don't need half this code anymore. ObjC++ objects can now have private C++ properties without any tricks, while maintaining a pure-ObjC interface.
Here is how you want to think about this problem:
Build a C++ object that is the delegate. Write all the code involved in setting up the delegation, etc, in C++. So when it says "pass a this pointer" you should really be passing a this pointer (because you should be doing this in the C++ code). The fact that you're doing a _bridge cast in a C++ call is a real hint something is going wrong.
Let an ObjC own the C++ object as a property.
Write the delegate callbacks in C++ inside the C++ object. If useful, you can let the C++ object then make calls into the ObjC object as needed, but it may be easier if the C++ object does all the delegate work.
I finally got this working, but had to remove the obj-c wrapper class from my viewController in order to do so. Here's what the code looks like:
ViewController.h
struct Opaque;
#interface ViewController : GLKViewController {
...
//RNWrap* opaqueCppWrap; // this didn't work
struct Opaque *opaqueCpp; // try this
...
}
ViewController.mm
// declare the Opaque structure
struct Opaque {
public:
Opaque() : cppobject() {};
myCppDelegate cppobject;
};
viewDidLoad
// ... create opaque member on initialization
opaqueCpp = new Opaque();
//opaqueCppWrap = [[RNWrap alloc] init]; // old way of doing things using wrapper
pass the delegate to the Load method
// old way using bridge cast and wrapper
//if(m_pEffect->Load(*m_pEffectParser, "Effect", c_szPfxFile,(__bridge myCppDelegate*)opaqueCppWrap, uiUnknownUniforms, &error) != PVR_SUCCESS)
// this works...
if(m_pEffect->Load(*m_pEffectParser, "Effect", c_szPfxFile, (myCppDelegate*)opaqueCpp, uiUnknownUniforms, &error) != PVR_SUCCESS)
Not sure why the wrapper class doesn't work, but I'm happy that my callback is working (appy no crashy!)
Phew, that was rough. Any thoughts/comments?