Doesn't complie on OS 10.10 conversion to ARC seems necessary

[telephon]

Trying to build according to instructions, I got the following:

Garbage Collection no longer supported

CompileC /Users/wanninger/Library/Developer/Xcode/DerivedData/Leonhard-gpyymcriphjihccuddmvaarzwigb/Build/Intermediates/Leonhard.build/Debug/Leonhard.build/Objects-normal/x86_64/main.o main.m normal x86_64 objective-c com.apple.compilers.llvm.clang.1_0.compiler
    cd /Volumes/data/git/Leonhard
    export LANG=en_US.US-ASCII
    /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang -x objective-c -arch x86_64 -fmessage-length=0 -fdiagnostics-show-note-include-stack -fmacro-backtrace-limit=0 -fobjc-gc-only -Wno-trigraphs -fpascal-strings -O0 -Wno-missing-field-initializers -Wno-missing-prototypes -Wno-implicit-atomic-properties -Wno-receiver-is-weak -Wno-arc-repeated-use-of-weak -Wno-missing-braces -Wparentheses -Wswitch -Wno-unused-function -Wno-unused-label -Wno-unused-parameter -Wunused-variable -Wunused-value -Wno-empty-body -Wno-uninitialized -Wno-unknown-pragmas -Wno-shadow -Wno-four-char-constants -Wno-conversion -Wno-constant-conversion -Wno-int-conversion -Wno-bool-conversion -Wno-enum-conversion -Wno-shorten-64-to-32 -Wpointer-sign -Wno-newline-eof -Wno-selector -Wno-strict-selector-match -Wno-undeclared-selector -Wno-deprecated-implementations -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.10.sdk -fasm-blocks -fstrict-aliasing -Wprotocol -Wdeprecated-declarations -mmacosx-version-min=10.10 -g -fvisibility=hidden -Wno-sign-conversion -I/Users/wanninger/Library/Developer/Xcode/DerivedData/Leonhard-gpyymcriphjihccuddmvaarzwigb/Build/Intermediates/Leonhard.build/Debug/Leonhard.build/Leonhard.hmap -I/Users/wanninger/Library/Developer/Xcode/DerivedData/Leonhard-gpyymcriphjihccuddmvaarzwigb/Build/Products/Debug/include -I/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include -I/Users/wanninger/Library/Developer/Xcode/DerivedData/Leonhard-gpyymcriphjihccuddmvaarzwigb/Build/Intermediates/Leonhard.build/Debug/Leonhard.build/DerivedSources/x86_64 -I/Users/wanninger/Library/Developer/Xcode/DerivedData/Leonhard-gpyymcriphjihccuddmvaarzwigb/Build/Intermediates/Leonhard.build/Debug/Leonhard.build/DerivedSources -F/Users/wanninger/Library/Developer/Xcode/DerivedData/Leonhard-gpyymcriphjihccuddmvaarzwigb/Build/Products/Debug -F/Volumes/data/git/Leonhard/build/Debug -F/Volumes/data/git/Leonhard -MMD -MT dependencies -MF /Users/wanninger/Library/Developer/Xcode/DerivedData/Leonhard-gpyymcriphjihccuddmvaarzwigb/Build/Intermediates/Leonhard.build/Debug/Leonhard.build/Objects-normal/x86_64/main.d --serialize-diagnostics /Users/wanninger/Library/Developer/Xcode/DerivedData/Leonhard-gpyymcriphjihccuddmvaarzwigb/Build/Intermediates/Leonhard.build/Debug/Leonhard.build/Objects-normal/x86_64/main.dia -c /Volumes/data/git/Leonhard/main.m -o /Users/wanninger/Library/Developer/Xcode/DerivedData/Leonhard-gpyymcriphjihccuddmvaarzwigb/Build/Intermediates/Leonhard.build/Debug/Leonhard.build/Objects-normal/x86_64/main.o

error: garbage collection is no longer supported