Xcode Build Script phase to check for retain cycles within blocks (self capture)

check-cycles.sh

#!/bin/sh
EXCEPTIONS=(
    ', '
    'animations:'
    'animateChanges:'
    'changes:'
    'completion:'
    'completionBlock:'
    'CompletionBlock:'
    'performAnimations:'
    'performWithoutAnimation:'
    'performAtomicBatchUpdate:'
    'performOffscreenRenderWithBlock:'
)
REGEX=""
for exception in "${EXCEPTIONS[@]}"; do
    REGEX="$REGEX(?<!$(sed 's/[][\.|$(){}?+*^]/\\&/g' <<< "$exception"))"
done
REGEX=$REGEX'\^\s*\{[.\s]*?self'

IFS=$'\n'
for line in `pcregrep --line-offsets -H -n --include='\.[mc]' -r -M "$REGEX" . 2>/dev/null`; do
    echo "$(sed -E 's/(.*):.*/\1/' <<< "$line"): warning: Possible retain cycle"
done