Linking Libraries in Xcode

Link External Library in Xcode C++ Project

If I understand correctly what you are asking, you simply want to "set" the file chooser dialog at the right place, right?

If so, you just have to press Cmd + Alt + G once you are in the file chooser dialog, after clicking on "Add Other..." in the "Link Binary with Libraries" menu. A "Go to the folder:" dialog comes up, and there you can type the fullpath to the file or the folder you are looking for.

Hope that helped!

How to link my static .a library to a c Xcode(10.2.1) project

It's old but maybe will work for you:

Go to your Project's Build Phases
Click on the "+" under "Link Binary With Libraries" to add a new library. Then click on the "Add Other" button.
Navigate to the static library file (.a) and add it.

https://www.chilkatsoft.com/xcode-link-static-lib

And then you should add your directory Build Settings > Library Search Path

Note: Not the full path, just the directory.

Linking a Static C Library in Xcode 7?

If this is an external static lib, you need to add the path it exists to Library Search Paths under Build Settings. Not the full path, just the directory it is in.

What are the libraries linking options in Xcode?

For dynamic frameworks built with carthage I usually use this setup:

Link the library with any target you want to use it in. You need this to be able to import the framework in your code.
Embed the library only in the containing app target. This will actually copy the framework in your app bundle. If you don't embed it your app will crash on startup, because your framework can't be found.

Only the app target is responsible for embedding all the frameworks and their dependencies. That way if an extension and the app both use a framework, it will be distributed with the app only once.

For the Xcode interface:

dragging a framework into General -> Embedded Binaries will add the framework to both "Link Binary With Libraries" and "Embed Frameworks" build phases
dragging a framework into General -> Linked Frameworks and Libraries will add the framework only to the "Link Binary With Libraries" build phase.

The views under General seem to be filled from the build phases tab so you can use either.

Hope that makes sense.

Edit: Target dependencies are just targets that need to be built before the current target can be built. So your app target would list its extension here, so that the extension gets built, whenever you build your app.

When to use dynamic linking library in iOS ? And what is advantage of using dynamic library in iOS?

Your understanding of dynamic and static libraries is correct.

Static Linking

The compiled source code (object code, the .o files) and the compiled library code are combined into a single executable [1]

Dynamic Linking

The compiled source code (object code) and the library code are not combined together. The references to the dynamically linked library are resolved at runtime while the app launches or while running (the second part is not applicable in the case of iOS Apps) [1]

Q1

iOS borrows heavily from MacOS on how its applications work. Executables in both the OSes are Mach-O files. Now, on macOS dynamically linked libraries or dylibs are intended and designed to be updated without having to update the entire app. And by design, this is possible in iOS as well. What prevents this is Apple's guidelines restricting apps from downloading executable code from the internet. Any new update has to go through their review process. [2]

Q2

Yes, some dynamically linked libraries are shared across apps. However, they are created and updated by Apple through iOS updates. All Apple frameworks like UIKit, SceneKit, etc are examples of this. This is why these frameworks are weakly linked in Xcode with the option 'Do Not Embed'

Q3

Using your own dylibs are not completely pointless. If you ship extensions in your app, then dylibs are an excellent option to share code between the app and extensions without increasing the binary size. In this case, the executables share the same library. [3]

[1] https://developer.apple.com/library/archive/documentation/DeveloperTools/Conceptual/DynamicLibraries/100-Articles/OverviewOfDynamicLibraries.html#//apple_ref/doc/uid/TP40001873-SW1

[2] https://developer.apple.com/app-store/review/guidelines/#app-completeness#2.5.2

[3] https://developer.apple.com/forums/thread/73802

When to link frameworks/libraries on Xcode?

You have to link frameworks and libraries that are not provided by Apple in OS. As frameworks like "AVFoundation" are dynamic libraries provided in OS.

If you have made your own framework/library or using others then you have to link and embed them also in your xcode project.

From Xcode 5 LLVM and Clang provide option to auto-link libraries and Frameworks.By default the vaule is true.
That's why Apple system frameworks(default frameworks) do not have to be explicitly linked to Xcode projects.
See Options in Apple Clang-language- Modules in build settings.
Hope it Helps