Spinner with SharedPreferences

Good evening. I'm trying to save the choice the user makes in Spinner in SharedPreferences, when he clicks OK, but I'm not getting it, can anyone help me? Then I want to redeem the choice made when it opens the application again and places it in a textView.

Follow my code.

 mShowDialog = (Button) findViewById(R.id.btnEscolhaCidade);

    mShowDialog.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            AlertDialog.Builder mBuilder = new AlertDialog.Builder(MainActivity.this);
            View mView = getLayoutInflater().inflate(R.layout.dialog_spinner, null);
            mBuilder.setTitle("Em qual Cidade Você está?");

            final Spinner mSpinner = (Spinner) mView.findViewById(R.id.spinner2);
            ArrayAdapter<String> adapter3 = new ArrayAdapter<String>(MainActivity.this,
                    android.R.layout.simple_spinner_item,
                    getResources().getStringArray(R.array.cidades));
            adapter3.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
            mSpinner.setAdapter(adapter3);

            mBuilder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialogInterface, int i) {
                    if (!mSpinner.getSelectedItem().toString().equalsIgnoreCase("Escolha uma Cidade")) {
                        cidade_Escolhida.setText(mSpinner.getSelectedItem().toString());
                        SharedPreferences.Editor editor = preferences2.edit();
                        editor.putString(getString(R.string.cidade_escolhida_salvo), mSpinner.getSelectedItem().toString());
                        editor.apply();

                                Toast.makeText(MainActivity.this,
                                mSpinner.getSelectedItem().toString(),
                                Toast.LENGTH_LONG)
                                .show();
                        dialogInterface.dismiss();
                    }

                }
            });

            mBuilder.setNegativeButton("Cancelar", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialogInterface, int i) {
                    dialogInterface.dismiss();

                }
            });
            mBuilder.setView(mView);
            AlertDialog dialog = mBuilder.create();
            dialog.show();
        }
    });