In my Xcode project,I added the same framework for ios7 and ios8.I have renamed them to xxx-ios7.framework and xxx-ios8.framework.
I want to use objc_getClass("someclass") to get the runtime class.But the two frameworks have the same class.
How shoud I know which class I will get?
Although this may not be a great answer, you may want to use the same mechanism that Microsoft used in their MFC classes, which is defining a version number.
In essence, you would have a method, or methods like:
- (NSString*)classVersionAsString;
- (NSInterger)classVersionAsNumber;
which would return meaningful version information for you.
As noted in the comment above, you should be careful with having multiple frameworks with the same class names, since, the loader will pick the first class that matches a linker requirement by the dependent module or dependent application. When the modules are loaded, the class you get might not be what you expected.
Related
I have a couple third-party libraries (not using cocoapods) in my iOS project, and when I dug into the files of each, I discovered that 4 of these libraries had their own versions of the UIImage+ImageEffects category. So I was about to merge them into one single file, but that got kind of messy:
For instance, one of the libraries, SCLAlertView, has a custom method inside its version of UIImage+ImageEffects which refers back to one of SCLAlertView's classes to access a variable. So if I import that class into the merged file, It would make the new UIImage+ImageEffects dependent on SCLAlertView. I dont feel comfortable about that, and its not pretty. So I need your guys thoughts on this :
What is the best approach to go about this? Should I just go ahead and merge them or keep them as separate files in their respective libraries?
Does having multiple, slightly different, versions of the same category in a project really matter? does it give rise to any issues/conflicts?
i often see this :
Class _NSZombie_OS_dispatch_group is implemented in both ?? and ?? ...
in my console. is this by any chance caused by the above thing?
Thanks in advance.
Note: I didnt give the question a generalized name like "multiple versions of same category in one project" because UIImage+ImageEffects is used by lots of libraries for blur effects and has the most chance of ending up as multiple slightly different versions in your project
Answering 2 will drive the answer to 1 (and 3 sounds like a bug in the system, you should file it :) ):
Does having multiple, slightly different, versions of the same category in a project really matter? does it give rise to any issues/conflicts?
As long as all method names are unique, there isn't a problem outside of the issue that categories on system classes are awful for the long term maintainability of a codebase.
If, however, the categories all have methods of the same name -- which they likely do -- then only one of them will be used and which one is indeterminate.
Thus, yes, you'll need to merge them. Or, better yet, eliminate them entirely by refactoring them into a helper class or something (then file a bug against the original codebase and have 'em pull the changes).
If you build and integrate your 3rd party libs as static libraries, every lib is isolated and uses its own version of the category, and things should work fine. In this case, you should keep the categories internal to the libs and avoid exposing them by means of #include in public headers. EDIT: As pointed out by bbum, category methods are not isolated inside their containing static lib; wrapping the libraries as static libs would not solve the OP's problem.
If you just have one build target and integrate the libs by source, things will work OK as long as the duplicate method implementations don't differ (even though this might result in lots of linker warnings).
Issue will arise if the category implementations differ, because the resulting behavior (i.e. which category method is used at runtime) is undefined (see this post). In this case, I don't know a good solution for the problem; a not good (but working) solution would be to rename (prefix) the methods in each lib's category and use the renamed method in the respective lib. E.g. in lib A, you would rename imageByApplyingLightEffectToImage: to a_imageByApplyingLightEffectToImage: and change all calls to that method inside A accordingly. As I said, I would use this approach as a last resort only.
I am a (very) novice iOS/Swift programmer with a basic question about moving reusable software objects to their own ... something.
I am developing three iPhone apps that present information from three distinct data sets. Those data sets contain unique information but are structurally similar. As such, the apps share some Swift classes that are identical, specifically the classes that model the data. As I continually refactor the code, I find that when I tweak a class in one app's project, I have to remember to go to the other two projects and make the same tweaks to the same classes for those apps. It's getting to be a big headache.
What I would like to do is have one class definition in its own ... something that I can share, link, import, or attach to/from each app's project. From my online research, I suspect that the ... something is a library? or maybe it's a framework? or a module? I have found all three terms are used, but I am not sure how they relate to each other.
Given that all of the software I am writing is in Swift, does Xcode support what I am trying to do? Thank you!
It seems you have the issue of needing the same Swift class in multiple projects. You could build a Framework (aka Module) for this class then copy it in to each project. This is probably the formally correct approach but it is a bit of overkill for just a single class.
Instead, you could just make the file in the Navigator panel a reference in each project to the one actual file.
You could also make a Workspace and then put each project into the workspace and just have the file at the top level (but this may introduce some build complexity).
Im currently working on a iOS project where we now want to add some feature for the Apple Watch. Since the extension for Apple Watch is a different target I naturally can't access the code written for the App. I have searched here on stackoverflow and have found two different ways to solve this problem.
Create a dynamic frameworks. This would definitely be the best approach but unfortunately the app must support down to iOS 6, and what I have found this solution will only work on iOS 8+.
Link the files in either Build Phases -> Compile Sources or through Target Membership in File Inspector. The main problem here is that the two classes we want to use have many dependencies to many other classes, which also have other dependencies and so on. From what I understand I need to include all these other files as well if I want to make use of the classes I intend to use in the extension.
So my question is if there is any other better way for me to accomplish this. If I choose #2, first of all I need to include all files, and after that, from a maintenance point of view, if I make changes to there files, for example importing an other class, I need to include that one as well in Compile Sources / Target Membership. Would really appreciate any ideas or advice regarding this! Thank you!
I don't know how "deep" is your coupling regarding point 2. However if you can use interfaces(protocols) instead of direct class referencing you can separate just the classes you need.
Moreover you could re-think whether specific class really need some other class to operate(probably not) or just some methods from it. Those methods could be moved to protocol and your dependant class to implement it(now this class do not need to be part of AppWatch target).
This will be heavy work though if your project is really big and your classes are tightly coupled. I would advice you to read this article about Dependency Injection and especially 'Dependency is bigger than Testing part' :)
I am asking my self if there are a way to add dynamic warning to my project.For exemple, every method in my class should begin by an analytics tag (setTagVorView:), if this line doesn't exists, I or other developers will be notified by a warning on this method.
Today, my only solution is to create a protocol (delegate) with a required method and every class (UIViewController for example) should follow this protocol and implements the required methods. The problem is : if the developer forgot the delegate, he will never be notified.
Another example, the appledoc command line tool add warnings to the project if some properties or methods don't have descriptions.
So how can i add my rules to predict warnings in some cases ?
Thank you.
Not sure if it fits your needs, but there is at least on way, hardcode way to achieve this goal: create a clang plugin and add there your own rules.
I'm not going very deep, because it might take too much time, but if you really interested in this solutions you can take a look at this blog-post, there is actually described a way to make the plugin with custom warnings and even errors
You could use NSAsserts in all the methods you want the developers to override:
NSAssert(NO, #"You need to implement this methode!");
It's, of course, not as elegant as compile time warnings.
Alternatively, you could create a XCode file template,with hardcoded warnings in. Take a look at this SO answer
I am very new to the field of ios programming and working with linker is just a whole new world to me. I would try my best to be precise about my question.
Context: Static library linking in an ios project using xcode.
Problem:
Problem members:
3 static libraries.
libTestLibA.a
libTestLibB.a
libTestLibB_mine.a -- same functionality as libTestLibB.a -- same classes/methods everything.
Problem description
I am making an app using libTestLibA.a.
libTestLibA has some classes that depend on some classes from libTestLibB. Hence libTestLibA.a has libTestLibB.a compiled in itself.
Now, I have my own library named libTestLibB_mine. It has the exact same functionality as that of libTestLibB. Same methods / classes for same functionality. I want libTestLibA to use libTestLibB_mine instead of libTestLibB. I just have compiled static libraries (.a) for each of the problem members , ie, libTestLibA, libTestLibB and libTestLibB_mine.
Question:
When I compile my application, can I force a static compiled library (libTestLibA.a) to make use of another library (libTestLibB_mine.a) instead of what it already contains (libTestLibB.a)? If yes, how? If not, is there some work around?
Much thanks.
If A has already been statically complied against B, then I don't think you can replace B with B_mine. But as a workaround, I think what you might be looking for here is "Method Swizzling". What it does is, at runtime, replace the method of a class with another method (intercept the message and direct it somewhere else).
The following links should be useful to you.
CocoaDev Method Swizzling
JRSwizzle - open source library to make swizzling easier
Be sure to read about the dangers of method swizzling too.