Duplicate Symbols for Architecture arm64

Below Patch work for me..:)

Step 1: Go to TARGETS -> Build Settings -> No Common Blocks -> No

Step 2: Go to TARGETS -> Build Settings -> enable testability -> No

**Setting it back to NO solved the problem!**

to solve this problem go to Build phases and search about duplicate file
like (facebookSDK , unityads ) and delete (extension file.o) then build again .

In my case reason was too stupid :

I had a Constant.h file where I had macros defined.
I thought of doing NSString there. and did this :


NSString const *kGreenColor = @"#00C34E";

this caused the problem of Duplicate Symbols for Architecture arm64
and Linker command failed with exit code 1. **Removing const NSString line worked for me.**

check your include file, I had this issue because I accidentally #imported "filename.m" instead of "filename.h", autocorrect (tab) put an "m" not "h".

Using Xcode 8, "Update project to recommended settings" option turned ON 'No Common Blocks' for my project.

Turning it back to OFF fixed everything up.

Another Solution is to:

> Select **Project** -> **Target** -> **Build phase** -> **Compile source** -> search
> for the file which is mentioned in the 3rd last error line (In your
> case **BFAppLinkReturnToRefererView.o**).

Then you will see either 1 or 2 files in search result.

**Remove** one of them and **compile again**. It should recompile now because there is only one file left and no more conflicts for build.

If that doesnt work the file probably has errors in it and you should remove all of them and then recompile.
It should work again.

For me, I created a method called `sampleMethod` in ViewController_A and created the same method in ViewController_B too, It caused me this error, then i changed the method name in ViewController_B to `secondSampleMethod`. It fixed the error.

Seems like a Good feature to reduce the code and not to duplicate the same code in many places.

I tried changing the No Common blocks from Yes to No then enabling testability from Yes to No. It didn't worked. I Checked duplicate files also in build phases, but there is no duplicate files.

I got this issue because I was lazily defining a variable in my .m outside of a method, then in another .m file I was defining another variable with the same name outside a method. This was causing a global variable name duplicate issue.

The problem for me was I had manually included a framework but then also included that same framework in CocoaPods not knowing I did so. Once I removed one or the other, the problem went away

I've messed up my pods while downgrading a pod and I've managed to resolve the issue with *duplicate symbols for architecture arm64* by removing the pods and installing them again with:

pod deintegrate
pod install