the error is that (in MAC):
An error occurred while trying to generate project files.
Running Mono…
Found mono via known Mono.framework path
Running installed mono, version: Mono JIT compiler version 5.16.0.179 (2018-06/6e48ad4f7b1 Wed Oct 3 14:05:19 EDT 2018)
/Users/Shared/Epic Games/UE_4.20/Engine /Users/Shared/Epic Games/UE_4.20/Engine/Binaries/Mac
Discovering modules, targets and source code for project…
Triggered an exception while looking for SDK directory in Xcode.app
System.IO.DirectoryNotFoundException: Could not find a part of the path ‘/Library/Developer/CommandLineTools/Platforms/MacOSX.platform/Developer/SDKs’.
at System.IO.__Error.WinIOError (System.Int32 errorCode, System.String maybeFullPath) [0x000f7] in <14f1e720d53a4a6a8800252bec102319>:0
at System.IO.FileSystemEnumerableIterator1[TSource].HandleError (System.Int32 hr, System.String path) [0x00006] in <14f1e720d53a4a6a8800252bec102319>:0 at System.IO.FileSystemEnumerableIterator1[TSource].CommonInit () [0x00054] in <14f1e720d53a4a6a8800252bec102319>:0
at System.IO.FileSystemEnumerableIterator1[TSource]..ctor (System.String path, System.String originalUserPath, System.String searchPattern, System.IO.SearchOption searchOption, System.IO.SearchResultHandler1[TSource] resultHandler, System.Boolean checkHost) [0x000d6] in <14f1e720d53a4a6a8800252bec102319>:0
at System.IO.FileSystemEnumerableFactory.CreateFileNameIterator (System.String path, System.String originalUserPath, System.String searchPattern, System.Boolean includeFiles, System.Boolean includeDirs, System.IO.SearchOption searchOption, System.Boolean checkHost) [0x00009] in <14f1e720d53a4a6a8800252bec102319>:0
at System.IO.Directory.InternalGetFileDirectoryNames (System.String path, System.String userPathOriginal, System.String searchPattern, System.Boolean includeFiles, System.Boolean includeDirs, System.IO.SearchOption searchOption, System.Boolean checkHost) [0x00000] in <14f1e720d53a4a6a8800252bec102319>:0
at System.IO.Directory.InternalGetDirectories (System.String path, System.String searchPattern, System.IO.SearchOption searchOption) [0x00000] in <14f1e720d53a4a6a8800252bec102319>:0
at System.IO.Directory.GetDirectories (System.String path) [0x0000e] in <14f1e720d53a4a6a8800252bec102319>:0
at UnrealBuildTool.AppleToolChainSettings.SelectSDK (System.String BaseSDKDir, System.String OSPrefix, System.String& PlatformSDKVersion, System.Boolean bVerbose) [0x0002b] in <2e961b185ef0428d9926745a7b9b2f9f>:0
WARNING: Exception while generating include data for UE4Editor: Invalid SDK MacOSX.sdk, not found in /Library/Developer/CommandLineTools/Platforms/MacOSX.platform/Developer/SDKs
Generating data for project indexing… 0%@progress ‘Generating data for project indexing…’ 50%
WARNING: Exception while generating include data for MyProject2Editor: Invalid SDK MacOSX.sdk, not found in /Library/Developer/CommandLineTools/Platforms/MacOSX.platform/Developer/SDKs
Generating data for project indexing… 50%@progress ‘Generating data for project indexing…’ 100%
ERROR: UnrealBuildTool Exception: Invalid SDK MacOSX.sdk, not found in /Library/Developer/CommandLineTools/Platforms/MacOSX.platform/Developer/SDKs
can anybody help to solve this problem? thank!