I want to know the value of "_lastNotificationReceivedBundleIdentifier" which is an instance variable of a class. The header is dumped from iOS springboard app.
#interface SBRemoteNotificationServer : NSObject <APSConnectionDelegate> {
NSMutableDictionary* _bundleIdentifiersToClients;
NSMutableDictionary* _environmentsToConnections;
unsigned _lastPlayedAlertSound;
NSString* _lastNotificationReceivedBundleIdentifier;
}
but the following code does not work:
%hook SBRemoteNotificationServer
-(void)noteApplicationFinishedLaunching:(id)launching{
NSLog(#"identifier=%#",_lastNotificationReceivedBundleIdentifier);
%orig;
}
%end
and the compiler error is:
error: ‘_lastNotificationReceivedBundleIdentifier’ was not declared in this scope
How do I access and log this NSString?
You could probably use the objective-c runtime capabilities and take a look at the method object_getInstanceVariable(the_object, "_lastNotificationReceivedBundleIdentifier", (void**)&yourPointer);
Another solution to try is:
[self valueForKey:#"lastNotificationReceivedBundleIdentifier"];
where self is the parent object and lastNotificationReceivedBundleIdentifier is the variable name. eg same as self.lastNotificationReceivedBundleIdentifier.
Related
I'm trying to bridge Swift 5 and the existing Objective c Function. Typically the Cordova request hits the Swift layer which inturn calls Objective C and returns back the result to Cordova. During compilation, I'm getting this error
NSLog(#"Result : %# ", result);
CDVPluginResult* pluginResult;
pluginResult = [CDVPluginResult resultWithStatus:CDVCommandStatus_OK messageAsString:result];
// Below line throwing "No known class method for selector 'commandDelegate'"
[[self commandDelegate] sendPluginResult:pluginResult callbackId:command.callbackId];
The commandDelegate property is an instance property, not a class property. The clue is in the error "No known class method" - the code above must be currently in a class method (denoted by + in ObjC), but the commandDelegate property can only be referenced from an instance method (denoted by -). self in this context is a reference to the class itself, rather than an instance of the class.
Make sure the enclosing function is an instance method (if that's what you need). Also make sure that your plugin is implementing the CDVPlugin interface (#interface MyPlugin : CDVPlugin in your plugin's header file), otherwise you won't be able to access the commandDelegate property.
Making it var to globals.
struct Globals {
static var sampleCommandDelegate: Any?
}
Can someone please explain to me (in simple terms) why an instancetype is used in Objective-C?
- (instancetype) init {
self = [super init];
if (self) {
// Custom initialization
}
return self;
}
It's to increase type safety.
Back in the old days, initialisers just returned an object of type id (any object).
With normal initialisers (those that begin with "init", "alloc" or "new"), this wasn't usually a problem. The compiler would automatically infer the type that it returned and therefore restrict any method calls on the object to the instance methods of that class.
However, this was a problem with static convenience initialisers or "factory methods" that didn't necessarily follow the same naming convention - therefore it was unable to apply the same type safety.
This means that with a class like this:
#interface Foo : NSObject
+(id) aConvenienceInit;
#end
The compiler would accept code like this:
NSArray* subviews = [Foo aConvenienceInit].subviews;
Why? Because the returned object could be any object, so if you try and access a UIView property - there's no type safety to stop you.
However, now with instancetype, the result you get back is of type of your given instance. Now with this code:
#interface Foo : NSObject
+(instancetype) aConvenienceInit;
#end
...
NSArray* subviews = [Foo aConvenienceInit].subviews;
You'll get a compiler warning saying that the property subviews is not a member of Foo*:
Although it's worth noting that the compiler will automatically convert the return type from id to instancetype if your method begins with "alloc", "init" or "new" - but nonetheless using instancetype wherever you can is a good habit to get into.
See the Apple docs on instancetype for more info.
Imagine two classes:
#interface A : NSObject
- (instancetype)init;
#end
#interface B : A
#end
The init method from A is inherited to B. However, in both classes the method has a different return type. In A the return type is A and in B the return type is B.
There is no other way to declare the return type for initializers correctly. Note that most programming languages with classes don't even have return types for constructors, therefore they completely avoid the issue.
This is the reason why Obj-C needs instancetype but of course it can be used outside initializers, too.
It is important to use instancetype instead of id in Objective-C if you are also using this code in Swift. Consider the following class declaration:
#interface MyObject : NSObject
+ (id)createMyObject;
- (void)f;
#end
If you want to create a MyObject instance in Swift 5.3 with createMyObject and then call f for this object, you will have to do the following:
let a = MyObject.createMyObject()
(a as? MyObject)?.f()
Now replace id with instancetype in MyObject to have the following Swift code:
let a = MyObject.create()
a?.f()
As you can see now, you can use MyObject.create() instead of MyObject.createMyObject(). And you don't need to use (a as? MyObject) since a is defined as MyObject? and not as Any.
I'm still new to Objective-C (coming from a Java and C# background), and I'm implementing a plugin system for an iOS SDK I'm developing.
I've defined my plugin header (Plugin.h) as follows (the java counterpath would be an abstract class, correct me if I'm doing anything wrong here).
#protocol Plugin <NSObject>
#required
- (void)initialize;
- (NSString *) getPluginName;
- (NSString *) getVersion;
#end
I then have a method in my SDK that can be used to register plugins. The array will be an array of objects that inherit from TFTPlugin.
+ (void)registerPlugins:(NSMutableArray*) array
{
for(Plugin *plugin in array)
{
[pluginClasses addObject:plugin];
}
}
But I'm getting an error at the for loop: Use of undeclared identifier 'plugin'.
Any idea what I'm doing wrong here?
Thanks
Try this:
for(id plugin in array){
if([[plugin class] conformsToProtocol:#protocol(Plugin)]) {
[pluginClasses addObject:plugin];
}
}
The checking to see if it conforms to the protocol is optional if you know that everything you are passing in actually does.
I am at my wits end with a property declaration in a iOS class. In my .h file I have the following declaration :
#property (strong, nonatomic)NSString *sessionID;
In my .m file I have this code :
- (void)setSessionID:(NSString *)aSessionID
{
_sessionID = aSessionID;
// Custom code to set this in a global context
}
This is all fine and compiles with no issues. Now I need to have the sessionID return a default value if nothing is set, however the moment I add this line :
- (NSString *)sessionID
{
return _sessionID ? _sessionID : #"defaultSession";
}
then the first line in the setSessionID:
_sessionID = aSessionID;
causes an error with "Use of undeclared function _sessionID. Did you mean aSessionID", I am at my wits end to figure out what is causing it.. I have so many classes with variables and have never seen this before... what is causing this? I restarted Xcode, cleaned out the project and no luck.. If I remove the - (NSString *)sessionID method, then it stops complaining.. but the moment I add the method declaration the Xcode marks it as an error.
Anypointers accepted! :)
Edit: I also noticed, that in this class if I add any property accessor method it complains about the ivar.. e.g. I have another property declared
#property (strong, nonatomic) NSString *userEmail
The moment I add -(NSString *)userEmail, the ivar _userEmail usage above it all becomes undeclared.. :(
If you override both the setter and getter of a property, the compiler will not automatically synthesize the backing ivar for you. You need to do a manual synthesis,
#synthesize sessionID = _sessionID;
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?