From c130cb697d530aa6d626782292f6aa495922fbd6 Mon Sep 17 00:00:00 2001
From: Jonathan Bagg <drwho@infidigm.net>
Date: Mon, 9 Oct 2017 21:30:17 -0400
Subject: [PATCH] Example now stops and starts service publish and service
 discovery when application is suspended (device sleeps) and becomes active
 (device wakes). Important on iOS devices as device sleep kills browser and
 service publisher.

---
 README.md          | 10 +++++++++-
 example/window.cpp | 37 ++++++++++++++++++++++++++++---------
 example/window.h   |  6 ++++--
 3 files changed, 41 insertions(+), 12 deletions(-)

diff --git a/README.md b/README.md
index a78174d..63c71ca 100644
--- a/README.md
+++ b/README.md
@@ -107,4 +107,12 @@ qDebug() << zcs->txt["Qt"];
 
 Qt5
 
-On Linux, libavahi-client-dev and libavahi-common-dev
\ No newline at end of file
+On Linux, libavahi-client-dev and libavahi-common-dev
+
+### Apple App Store deployment
+
+Publishing GPL software in the App Store is a [violation of the GPL](https://news.ycombinator.com/item?id=3488833).  If you need to publish an app in the Apple App Store that uses QZeroConf, please contact me for a copy of QZeroConf with a BSD licence.
+
+### iOS device sleep
+
+When iOS puts the device to sleep, it breaks the DNS-SD browser and service publisher.  The only way around this is to call stopServicePublish() and stopBrowser() when the application state changes to Qt::ApplicationSuspended (sleep) and then call start startPublish() and startBrowser() when the application state changes to Qt::ApplicationActive (wake).  See appStateChanged() in example.
diff --git a/example/window.cpp b/example/window.cpp
index f58e85f..757f4a9 100644
--- a/example/window.cpp
+++ b/example/window.cpp
@@ -24,6 +24,7 @@
    Example app to demonstrate service publishing and service discovery
 ---------------------------------------------------------------------------------------------------
 **************************************************************************************************/
+#include <QGuiApplication>
 #include <QVBoxLayout>
 #include <QPushButton>
 #include <QTableWidgetItem>
@@ -54,9 +55,9 @@ mainWindow::mainWindow()
 
 	connect(&zeroConf, SIGNAL(serviceAdded(QZeroConfService *)), this, SLOT(addService(QZeroConfService *)));
 	connect(&zeroConf, SIGNAL(serviceRemoved(QZeroConfService *)), this, SLOT(removeService(QZeroConfService *)));
+	connect(qGuiApp, SIGNAL(applicationStateChanged(Qt::ApplicationState)), this, SLOT(appStateChanged(Qt::ApplicationState)));
 
-	zeroConf.startBrowser("_qtzeroconf_test._tcp");
-	startPublish();
+	publishEnabled = 1;
 }
 
 void mainWindow::buildGUI()
@@ -68,13 +69,13 @@ void mainWindow::buildGUI()
 	button->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed);
 	layout->addWidget(button);
 	layout->setAlignment(button, Qt::AlignHCenter);
-	connect(button, SIGNAL(clicked()), this, SLOT(startPublish()));
+	connect(button, &QPushButton::clicked, this, &mainWindow::startPublishClicked);
 
 	button = new QPushButton(tr(" Disable Publish "));
 	button->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed);
 	layout->addWidget(button);
 	layout->setAlignment(button, Qt::AlignHCenter);
-	connect(button, SIGNAL(clicked()), this, SLOT(stopPublish()));
+	connect(button, &QPushButton::clicked, this, &mainWindow::stopPublishClicked);
 
 	table.verticalHeader()->hide();
 	table.horizontalHeader()->hide();
@@ -102,21 +103,39 @@ QString mainWindow::buildName(void)
     return name;
 }
 
+void mainWindow::appStateChanged(Qt::ApplicationState state)
+{
+	if (state == Qt::ApplicationSuspended) {
+		zeroConf.stopServicePublish();
+		zeroConf.stopBrowser();
+	}
+	else if (state == Qt::ApplicationActive) {
+		if (publishEnabled && !zeroConf.publishExists())
+			startPublish();
+		if (!zeroConf.browserExists())
+			zeroConf.startBrowser("_qtzeroconf_test._tcp");
+	}
+}
+
 // ---------- Service Publish ----------
 
 void mainWindow::startPublish()
 {
-	if (publishEnabled)
-		return;
-	publishEnabled = 1;
-
 	zeroConf.clearServiceTxtRecords();
 	zeroConf.addServiceTxtRecord("Qt", "the best!");
 	zeroConf.addServiceTxtRecord("ZeroConf is nice too");
 	zeroConf.startServicePublish(buildName().toUtf8(), "_qtzeroconf_test._tcp", "local", 11437);
 }
 
-void mainWindow::stopPublish()
+void mainWindow::startPublishClicked()
+{
+	if (publishEnabled)
+		return;
+	publishEnabled = 1;
+	startPublish();
+}
+
+void mainWindow::stopPublishClicked()
 {
 	if (!publishEnabled)
 		return;
diff --git a/example/window.h b/example/window.h
index b259b50..b4a53f1 100644
--- a/example/window.h
+++ b/example/window.h
@@ -40,14 +40,16 @@ public:
 
 private:
 	void buildGUI();
+	void startPublish();
 	QString buildName(void);
 	QTableWidget table;
 	QZeroConf zeroConf;
 	bool publishEnabled;
 
 private slots:
-	void startPublish();
-	void stopPublish();
+	void appStateChanged(Qt::ApplicationState state);
+	void startPublishClicked();
+	void stopPublishClicked();
 	void addService(QZeroConfService *item);
 	void removeService(QZeroConfService *item);
 };