#include <QCoreApplication>
#include <QLocale>
#include <QCollator>
#include <QtDebug>
int main( int argc, char* argv[] )
{
    QCoreApplication app( argc, argv );
    QLocale::setDefault( QLocale::Swedish );
    QString s1 = "a";
    QString s2 = "b";
    QString s3 = "o";
    QString s4 = "z";
    QString s5 = "å";
    QString s6 = "ä";
    QString s7 = "ö";
    qDebug() << "s1=" << s1;
    qDebug() << "s2=" << s2;
    qDebug() << "s3=" << s3;
    qDebug() << "s4=" << s4;
    qDebug() << "s5=" << s5;
    qDebug() << "s6=" << s6;
    qDebug() << "s7=" << s7;
    qDebug() << "QString::localeAwareCompare( s1, s2 )=" << QString::localeAwareCompare( s1, s2 );
    qDebug() << "QString::localeAwareCompare( s2, s3 )=" << QString::localeAwareCompare( s2, s3 );
    qDebug() << "QString::localeAwareCompare( s3, s4 )=" << QString::localeAwareCompare( s3, s4 );
    qDebug() << "QString::localeAwareCompare( s4, s5 )=" << QString::localeAwareCompare( s4, s5 );
    qDebug() << "QString::localeAwareCompare( s5, s6 )=" << QString::localeAwareCompare( s5, s6 );
    qDebug() << "QString::localeAwareCompare( s6, s7 )=" << QString::localeAwareCompare( s6, s7 );
    return app.exec();
}

s1= "a"
s2= "b"
s3= "o"
s4= "z"
s5= "å"
s6= "ä"
s7= "ö"
QString::localeAwareCompare( s1, s2 )= -1
QString::localeAwareCompare( s2, s3 )= -1
QString::localeAwareCompare( s3, s4 )= -1
QString::localeAwareCompare( s4, s5 )= 1
QString::localeAwareCompare( s5, s6 )= 1
QString::localeAwareCompare( s6, s7 )= -1

s1= "a"
s2= "b"
s3= "o"
s4= "z"
s5= "å"
s6= "ä"
s7= "ö"
QString::localeAwareCompare( s1, s2 )= -1
QString::localeAwareCompare( s2, s3 )= -1
QString::localeAwareCompare( s3, s4 )= -1
QString::localeAwareCompare( s4, s5 )= 1
QString::localeAwareCompare( s5, s6 )= -1
QString::localeAwareCompare( s6, s7 )= -1

    QCollator collator(QLocale::Swedish);
    QStringList list = {s7, s1, s2, s3, s4, s5, s6 };
    std::sort(list.begin(), list.end(), collator);
    qDebug() << "list=" << list;