在xcode12.5.1上FBClassStrongLayout 编译时报错
Cannot initialize a parameter of type 'id<NSCopying> _Nonnull' with an rvalue of type 'Class'
解决方法（亲测有效）：
在podfile文件最后一行加入下面代码，然后在pod install 一下，重新编译即可。
post_install do |installer|
## Fix for XCode 12.5
find_and_replace("Pods/FBRetainCycleDetector/FBRetainCycleDetector/Layout/Classes/FBClassStrongLayout.mm",
"layoutCache[currentClass] = ivars;", "layoutCache[(id<NSCopying>)currentClass] = ivars;")
end
def find_and_replace(dir, findstr, replacestr)
Dir[dir].each do |name|
FileUtils.chmod("+w", name) #add
text = File.read(name)
replace = text.gsub(findstr,replacestr)
if text != replace
puts "Fix: " + name
File.open(name, "w") { |file| file.puts replace }
STDOUT.flush
end
end
Dir[dir + '*/'].each(&method(:find_and_replace))
end