and juce already has a file sorter ! 
Array<File> files;
getFolder().findChildFiles (files, File::findFilesAndDirectories, false);
bool putFoldersFirst = false;
File::NaturalFileComparator sorter (putFoldersFirst);
files.sort (sorter);
and juce already has a file sorter ! 
Array<File> files;
getFolder().findChildFiles (files, File::findFilesAndDirectories, false);
bool putFoldersFirst = false;
File::NaturalFileComparator sorter (putFoldersFirst);
files.sort (sorter);