Xcode 8 Beta 3 Use Legacy Swift issue

If you are using CocoaPods and want it to be fixed automatically every time you are doing a pod install, then you can add these lines to the end of your Podfile:

post_install do |installer|
    installer.pods_project.targets.each do |target|
        target.build_configurations.each do |config|
            config.build_settings['SWIFT_VERSION'] = '3.0'
        end
    end
end

EDIT: This problem is now fixed if you use CocoaPods v1.1.1 or later. Don't forget to remove the ALWAYS_EMBED_SWIFT_STANDARD_LIBRARIES setting from your main project targets.

I just found a way to fix it.

Go to the Build settings of the project or library and set the Swift Compiler Version attribute "Use Legacy Swift Language Version" from Unspecified to Yes or NO.

https://i.stack.imgur.com/XgdA9.png

I have been ignoring this problem for a while now and just working on other stuff in the meantime - I finally found the solution to my problem.

Since my project is Objective-C I figured maybe one of the Pods I am using was using Swift, I checked each Pod and none of them were.

The final solution was that my Core Data model was set to generate code in Swift even though I have been manually generating them in the File > New > NSManagedObjectSubclass menu. All I had to do was switch it to Objective-C.

https://i.stack.imgur.com/Jk0ma.png

This issue is also visible in Xcode-8.1 . When we add new Target like Extension or Widget and Third party library is integrated in new target with the help of cocopods. After Pod install . We can face same error as above .

Change the Use Legacy Swift Language Version in every Library Build Setting to

No.

https://i.stack.imgur.com/tcw8L.png

If you are using Xcode 8 or later

Go to Build Settings Find use legacy swift language version Yes - Swift 2.3 No - Swift 3.0

Add below code in end of the podfile.

post_install do |installer|
  installer.pods_project.targets.each do |target|
    target.build_configurations.each do |config|
      config.build_settings['SWIFT_VERSION'] = '3.0'
    end
  end
end

I'm working on a project which has mixed objective-c and swift code I previously used swift version 2.3 and after upgrading to swift 3 I was unable to build the project. Xcode complained with the mentioned error message.

Apparently, there was still some outdated Swift version specified in my project.pbxproj file. There was swift 3.0.1 specified:

SWIFT_VERSION = 3.0.1;

Whereas, I already had 3.0.2 installed:

$ xcrun swift -version
Apple Swift version 3.0.2 (swiftlang-800.0.63 clang-800.0.42.1)
Target: x86_64-apple-macosx10.9

Sooo, I fixed it by changing the Swift version in the project-pbxproj file to:

SWIFT_VERSION = 3.0;

Seems the patch level version specifier was too specific.

In my case I have Just do the Following things

Choose project Target=>Go to Build setting=>Search for “Swift Language Version” =>give Value the current Swift version

Thats all It has fixed my Issue

https://i.stack.imgur.com/ycrVX.png

https://i.stack.imgur.com/MNT2B.png

Here are the steps.
1=> select your target from Xcode
2=> go to build setting
3=> search for "Swift Language Version"
4=> change it to swift 3. (or accordingly.)

set "Use Legacy Swift Language Version" to "YES" if you using a old version of swift in your project or any swift 3rd party. "No" if your project uptodate to current swift version. if you don't configure your swift version , after every update and Install, Pod framework need to specify this.

I actually had to do a search for "Legacy Swift" to be able to change it from unspecified to "Yes" When I simply scrolled down to the section described above, I was not able to change it. I hope this will help someone.

https://i.stack.imgur.com/z9pam.png

I was having this same issue and solved it by doing the following:

In Project > Build Settings:

Always Embed Swift Standard Libraries = $(inherited) Use Legacy Swift Language Version = YES

Then in my Podfile:

config.build_settings['SWIFT_VERSION'] = '3.0'

Using these three settings removed all warnings and allowed me to compile properly.

The most obscure and what actually got progress for compiling was changing the SWIFT_VERSION in the Podfile from 3 to 3.0 as suggested here.

From XCode 8 onwards, you can use swift 2.3 even though XCode 8 uses swift 3.x as default swift version. To use swift 2.3, just turn on flag Use Legacy Swift Language Version to YES from Build Setting, then XCode will use Swift 2.3 for that project target.

Before trying complicated solutions, here is a basic check you need to do if you are new to Cocoapods and you are having this issue.

You might need to:

Open your Podfile again

Check that the line for platform is not commented out with a '#'. It should finally look like something like :

platform :ios, '10.1' # Put the right version and no #platform here use_frameworks! # For swift pod "MyPod" # Your mean pod :)

Save your Podfile, Close Xcode, and Run pod install again

Open your project.xcworkspace

Maybe it's just that.

If not, you can go above ;-)

https://i.stack.imgur.com/qdV1G.png

Used this fix with Alamofire and other libs and all works ok.

Go to Project Build Setting for project and Target do below two.

ALWAYS_EMBED_SWIFT_STANDARD_LIBRARIES = YES
And
Swift Compiler - Version  = Swift 3

Change to latest Swift 3.

Error resolved.

If it's resolved your error fix, please like it.

In Xcode 9 beta. Go to Project Settings, Build Settings, search for Swift Language Version. In Xcode 9 you must specify if you are using Swift 3.2 or Swift 4.

If you change ALWAYS_EMBED_SWIFT_STANDARD_LIBRARIES to NO still not work, it is because the xcode issue, not your problem. Doing the follow steps:

1.Change ALWAYS_EMBED_SWIFT_STANDARD_LIBRARIES property to be YES on the warning target

2.then it will show an warning on left bar which recommend you change to swift 3.0

3.then change back to NO. Rebuild the project, the xcode finally detect your change to NO!

Problem solved in this case!