# Finding Swift files that need to be migrated **URL:** \ **Category:** Using Swift\ **Tags:** swiftc\ **Created:** [December 11, 2020, 12:14pm UTC](https://forums.swift.org/t/finding-swift-files-that-need-to-be-migrated/42730 "2020-12-11T12:14:10Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![lukzett](https://avatars.discourse-cdn.com/v4/letter/l/b5e925/32.png) [@lukzett](https://forums.swift.org/u/lukzett)\ **Post date:** [December 11, 2020, 12:14pm UTC](https://forums.swift.org/t/finding-swift-files-that-need-to-be-migrated/42730/1 "2020-12-11T12:14:10Z")
In Xcode I get a warning when opening my project: ```swift The target "XYZ” contains source code developed with Swift 3.x. This version of Xcode does not support building or migrating Swift 3.x targets. ``` I can't however find which Swift files need to be migrated. Here's what I have done: ```swift find . | grep -i "\.swift$" | while read l; do swiftc -parse -swift-version 5 "$l"; done ``` and ```swift find . | grep -i "\.swift$" | while read l; do swiftc -parse -runtime-compatibility-version 5.0 "$l"; done ``` Both commands terminate without error. Doesn't this mean that in fact all my swift files are written for the latest Swift? If not, what can I do? I should also mention: Xcode builds the app just fine. It's just that warning that irritates me. P.S.: I can't migrate because the required Xcode version 10.1for some reason will not launch. ---
**Author:** ![harlanhaskins](https://sea2.discourse-cdn.com/swift/user_avatar/forums.swift.org/harlanhaskins/32/333_2.png) [@harlanhaskins](https://forums.swift.org/u/harlanhaskins)\ **Post date:** [December 11, 2020, 2:22pm UTC](https://forums.swift.org/t/finding-swift-files-that-need-to-be-migrated/42730/2 "2020-12-11T14:22:30Z")
You can change the ‘Swift Language Version’ build setting to Swift 5 to tell Xcode that the sources have been migrated already.