I'm new to iOS dev (Java native) and I was kinda confused on how an app is compiled. I'm assuming it goes from the main.m file in the Supporting Files folder, which hands off command to the AppDelegate. Then depending on the state of the app (like didFinishLaunchingWithOptions, or applicationWillResignActive) it runs the commands in that method.
So if like my didFinishLaunchingWithOptions sets the window.rootViewController to another file - WXController, for example, it then passes control to WXController and runs all the methods in there in a sort of 'while-loop-esque' way?
Is my understanding even close to how compiling and building actually is?
You did assume wrong. But this is neither the case for Java!
If you are interested what happens when you build your project, you can click in Xcode on your project file (usually the top most in the file menu, unless you are using workspaces). These are the project settings. One of it's tabs is calles 'Build Phases'. Here you can see listed what the compiler will do and in which order!
But to give you a quick introduction on how things work in C and C similar programming languages: There are the source files and the header files. Usually all source files ( the ones that contain your actual code in case of objective-C these are the .m-files) are compiled in random order (ofc. there is an order, but it is not important since the source files should never reference each other! ). The header files (.h-files) are used to tell the compiler about all the variables and methods that are supposed to be contained in other source files. This information will be kept as references while compiling the sources and then later used for linking everything together. After everything is compiled (result are the object files *.o),the references generated from the header files linker flags are used to link all your objects together.
Related
I have code for a VST plugin and need to port some of it to an iOS app.
I have tried building the OSX version and using the lib.a and it doesnt work. When I open the iOS version of it, Xcode shows that it is missing the tagret.
If I copy the code directly into Xcode with all the JUCE modules, and I set the header search paths, I get compilation errors on things like no such type for String
After this latest JUCE update, Xcode would give the same errors until I updated the JUCE file itself, so I think the JUCE build settings or configuration of the new version is doing something differently. How can I get this code into a different Xcode project, so that I can use it?
Can I compile it as a library and use the objects through the header?
JUCE is designed to be included in projects generated by the Introjucer / Projucer (the JUCE project management tool). Without this, the correct preprocessor definitions will not be set up.
If you really needed to include JUCE source code inside your program, you could manually set up these preprocessor definitions (take a look at the AppConfig.h header from a generated project to get an idea of how much work this will be), but you'd really be going against the normal "JUCE way".
Simply including the headers and linking against the library will not work without considerable effort, as the include structure is ... odd ... and there isn't any library to link against directly anyway (the generated projects contain all the JUCE source normally, so there's no need).
Adding the JUCE source files (i.e. .cpp and .mm) to be compiled in a project directly will result in compilation errors, as they need to be compiled in a very specific order which is mandated by the header file (the header files #include certain implementation files after setting up their dependencies).
In short, if you can at all I would advise generating the project with the Projucer and adding other source files in as you need them, rather than the other way around.
From the beginning of my project, I use a custom framework, let's call it "custom.framework". But there was a bug in this framework and now I want to use another version of the "custom.framework".
At first, I simply removed the "custom.framework" file from my project and added the new one. But nothing changed, the bug was still there.
After multiple tries and hours, I understood that Xcode add the old version in memory and used this one instead of the new version. I know it because in the new version I added a method and when I cmd+click the class I've add the method into, it's not there and the file's path is unavailable.
Searching through the web, I tried to change some version parameters to my framework projects: Compatibility version, Curent Library version, Framework version. But this didn't change anything to Xcode which keeps using the old version.
I also tried to make the framework's project as a sub-project and add resulting framework as a dependency to my target. It worked well, but as the framework's project is on a separated remote git repository, I don't think this is an acceptable solution.
So my last try was to build a "custom2.framework", to force Xcode to use the real file and not some cached version. But again, it doesn't work and when building I get errors telling me that all my classes in custom2.framework are duplicated symbols of its cached version of "custom.framework".
So my question is simple: how can I finally tell Xcode to deleted its cached old version and let me use the file I gave him? I already tried to delete my project's derivedData but it seems cached frameworks aren't there.... I'm so desperate :(
Edit: Here are 2 screenshots to illustrate the issue
First screenshot is the path as shown by Xcode when I opened the file from the .framework object in the project navigator.
Second screenshot is the path as shown by Xcode when I opened the file from a cmd+click to a "DCEquipmentManager" in code.
As you can see, the framework linked with the code is not the framework in the project.
it seems problem with binding in new framework, your project still linked with old framework files.
try to remove all files and folder related to your "custom.framework and also remove path for that framework from project setting--> build setting --> search Path
Then after Drag and Drop Your "custom.framework" files in project.
it works for me.hope it resolve your problem.
Please try to clear derrived data:
Window -> Organizer
at the right side you will see projects list. Find your project and tap on it. I the top part of window you will see button delete in front of Derrived data, tap on it.
I guess it will solve your problem.
It might sound silly, but sometimes restarting XCode or the whole machine fix things.
Did you remove the old framework from Build Phases --> Link Binary With Libraries?
Use Clean Build Folder: option-shift-command-K, or select it from the Product menu when holding down the alt/option key.
First lets say something upfront. The build stage is a(are) command line tool(s) that is managed by Xcode according to your Build Settings.
So when Xcode doesn't find your Framework - the Build System will usually also not find it. This forces you to act but may end up in confused Xcode to catch an older reference.
Yes it may happen that the Header Xcode is pointing to is correct but the build system still uses an old copy somewhere. An outdated copy can dangle around literally anywhere depending on the steps you took before.
It (Xcode) assumes where it is located but the Build System still uses another version or the Search Paths just pointing in the wrong Locations even if they are visible to you and even your Framework icons are visible in the lists. So when you erase the last build you actually only force Xcode to rebuild from the known arguments, the settings stay the same, the lists stay the same. Even restarting Xcode does not change anything, the problem persists.
Ergo: Compiler Instructions, Xcode settings and Build System settings don't match what the code tells with #import <NAME/Name.h>
So you will check at least those 6 stages again:
Is your Framework Header File published in your Framework project?
are Build Settings really pointing to the right Framework Search Paths or System Framework Search Paths?
Is your Framework in linking list?
Is your Framework in Embed Framework list?
Does your framework appear in the Framework Group Folder in Workspace/Project Browser? (usually the very last Group Folder in the Browser below all your other files)
Is my Folder Structure correct?
At least 1 to 4 must be right otherwise it will fail.
Here a random list of common causes
Framework is located outside your Source Paths structure
Structure got changed after you added it to the project
You use Workspace's where Framework development and Final Application can appear side by side but you assume Xcode uses this to change its Search Paths
The contained build settings are misleading from former drag and drop operations, ending up tricking Xcode in the "wrong" corner. In this case recreating a project is just one of the possible ways to fix it but not the solution.
Also dragging a Framework into your Project > General or separated in Build Phases > Link Binary list or Embed Framework lists does not make Xcode aware of the wrong Build Settings.
The Linking works, embedding works, but compiling does not. The Header information is still missing.
The solution must be to correct your Build Settings.
As mentioned above Build System and Xcode are two different things. In particular only setting the right Framework Search Paths will solve those issues, even if you managed to kick your derived data manually.
Erasing Derived data?
Derived data is the place where precompiler collects data to compile. So it can be seen as expression of what all the settings are told to do. Erasing it does of course not change the settings but may fix inconsistencies related to former Build Settings. It would erase the derived data and rebuild from the Build System Settings you gave.
Correcting Linking?
Also Linking is not the same as making Xcode aware of the desired Headers. Linking is for your final Product to know where Symbols are to call on them at runtime, it does not change Framework Search Paths and System Framework Search Paths, they stay the same as given.
But it is not wrong to start fixing first with
Product > Clean Build Folder, it forces your build to parse all and compile all again on the next Build.
When the troubles come up because of folder structure in parallel or Frameworks are simply placed outside the Source Directory then you must point to them directly or relative.
Most likely you should place one extra entry in your Framework Search Paths like $(SRCROOT)/../Yourframeworksource/build/Debug. expression to point to relative higher folder structure.
Needless to say that a Release Build likely needs another entry ending in "/Release".Hint: Well you can have different Search Paths for different Compile Schemes..
This works particular good after you cleaned Linking List, Embed Frameworks List and then also check the very last Group Folder "Frameworks" for double entries to drag and drop a fresh Framework reference in there.
How to know if leading /../ will fix it?
Click on the dropped Framework Icon inside the workspace Framework Group Folder (lower most) while your Project is the active selected to work on, now watch for the relative Path information on the very upper right side of Xcode, if there is some /../ you know you need it as well.
Sorting of Framework Search Paths
play a role of course, just the same as #import/#include rule sorting matters.
Remember the first found, first wins rule because often we use #import that works different then #include but ignores second attempts to declare. This leads to once wrongfully declared headers to hide corrected declarations later on in parsing that share the same filename or define rules
#ifndef xyz
#define xyz
// all your code here.
// a second read attempt would be ignored
// a second read is hidden also when you use #include then.
#endif
So you can sort those entries either by code and/or in the build settings if needed because of course it matters what is declared before other declarations depend on it.
I'm writing a program for iOS and want to use the Apache Portable Runtime and the Subversion C library in my project.
Since this is the first time I'm trying to do this I have no idea where to start.
I already made a new C/C++ library project, imported all apr.h and svn.h files in the project, set the sdk to iOS7
It compiles well and it outputs an .a file but when I import it into my project it doesn't get linked or something.
Could anybody know a tutorial or maybe a svn library for objective c? Or at least point me in a right direction.
The only results I get while googling it are:
"Objective-C should support C Libraries natively, this should be very easy"
Not so easy for me I suppose. ;)
This is how you can troubleshoot:
Click your blue project icon.
Select the Build phases tab in your main view.
Expand "link with libraries".
Make sure your .a file is in this list. If not add it.
If you still have problems check your build logs (right most icon on left pane). The build logs contain a long list of what your compiler did. There are icons to the far right looking like 5-6 lines on top of each other. Actually the icon is hidden until you hover over it.
Clicking this will expand a compiler step and show you exactly what arguments were provided to your compiler. This will be pretty long so it might be smart to copy to an editor. But it will contain switches such as -I for including header files, -L for location of libraries etc. Check that your .a file is in fact included during compilation of the code which depends on it. Should be a -l switch I believe.
If you have the sourcecode of the C project, you can directly put all the source code into your project. Xcode knows how to compile C code and it will just be compiled with the rest of your project.
As mentioned by #Adam-Smith, you can directly interface with the C objects in your Objective-C code and the C objects will not be managed by ARC
I am testing an image capture library that sent over their code library as a regular header file and a file ending in a "*.a" extension. I am not familiar with using a file in this format and can't seem to find the right "magic" to search for.
What does this file extension stand for?
What if any extra steps are needed to get it integrated with my XCode project?
Maybe a bit more of theory can get you in the right track so you'll know how to search next time:
.a files are archives of object (.o) files. These object files are generally produced by an assembler, compiler, or other language translator; They contain machine code that is usually not directly executable, but are used by linker tools to generate an executable or yet another library by combining parts of these object files.
Another important thing you should know is that since these files contain machine code, they must have been compiled for the correct architecture you're targeting for (ex.: armv7, i386, etc). That can be the reason why sometimes you will be able build your project for one device but not to another if you don't have the right set of files for the targeted platform (e.g. iPhone simulator vs. actual iPhone).
It is also possible to have "universal binaries", which are files that in turn package together archives of object files (.a) for different architectures (e.g. using tools such as lipo), so that the same library file can be given to the linker for multiple architectures. Or, you may have a different linker configuration for each target (e.g. using conditional build settings in XCode). All of these files can be analyzed with certain tools (e.g. "file", "otool", "lipo -info", etc), and each has several parameters to play with. Debuggers will also check the symbols within these files for their own purposes.
When you drag the '.a' file to your project's directory within Xcode, you can notice that it will automatically add this file to the list of "Link Binary With Libraries" items under your target's "Build Phases".
Since the header files allows us to separate certain elements of a program's source code into reusable files, that commonly contain forward declarations of classes, subroutines, variables, and other identifiers that are needed for reference during the compilation step, it is common to have libraries provided as archives of compiled objects (.o) in ".a" files along with their respective headers. For instance, as soon as you include the headers files in your XCode project, the editor will provide auto-complete for these new functions.
Sometimes, you might also consider having the actual source code of the library instead of binaries inside your project as this * might * make debugging easier in case an unexpected behavior is happening inside that "library" package. Many times this is not an option though (when you have no access to the sources) when the binary distribution is made in purpose to hide implementation details (commercial libraries).
.a stands for archive. It is also known as a static library. I believe you should be able just to drag it and the header files into Xcode. Xcode should pick up the right thing to do from its extension.
Example, see appr. from 30 sec here
http://memention.com/ac3dreader/usage/quickstart.html
Another example from Google Analytics, under Setup
Drag GANTracker.h and libGoogleAnalytics.a from the SDK's Library directory into your new project.
https://developers.google.com/analytics/devguides/collection/ios/devguide
I want to make changes to the xmldom and XMLDoc files. I tried to, but I don't know how to test those changes because the program does not seem to be running the code in those files. I tried using a ShowMessage to see if that code was being accessed but it never showed up. Even if I rename the directory the files are in, the program still compiles fine as if it is not actively reading the files at run time but instead has the information stored elsewhere.
How can I change these namespaces and then make sure that the changes are being included in my next compile?
Update
Well i'm looking for an answer in general.. Because I have had this problem in multiple situations.. But for specifics Changing XML node attribute value gives "Namespace error" (here the answer talks about changing the 'AdomCore_4_3') I want to be able to change it and have the change show up when I compile.
If you've removed the compiled DCU files from your environment, and your changes still aren't being compiled into your project, then you either aren't really using those units at all, or you have run-time packages enabled.
With run-time packages, the compiled code is accessed from the BPL file, not the DCUs. You're not allowed to distribute modified BPL files, so if you're going to modify the Delphi-provided source code, you need to make sure you're not linking the package with the XML units to your project. You can control that in your project's linker options.
As long as you are not making changes in the interface section of the units, only the implementation section, then you can disable use of Runtime Packages in your Project Options and then add the modified source files directly to your project. The compiler will compile them into new .DCU files and use them instead of the default .DCU files.