Check supported architectures of framework in Objective-C

Each framework is really just a directory - not even like a package directory, but a plain directory you can browse directly into with Finder. Go into the .framework folder, at the top level you'll find a file with the same name as the framework (for older frameworks that file may be located under a folder called Versions/A within the .framework folder).

That file is really a static library (.a) file, just without the extension. Check it as you would any static library (using file or lipo -info) and you'll see what binaries the file contains.

You'll also know through XCode though. If you switch your project to support arm64 and the libraries you are linking to do not have arm64 support, XCode will not finish linking when compiling for a device.

Check below command in Terminal
lipo -info yourlib.a

Output like :
Architectures in the fat file: yourlib.a are: i386 x86_64 armv7 arm64

In case Framework.framework

Go to inside framework like below
cd /Your_Path_/CocoaLumberjack.framework

then run command
lipo -info CocoaLumberjack