URL Schema - Qt and Mac

Question

I am trying to implement my own URL scheme for my application. I have added the necessary lines for my Info.plist. After calling the specified URL (for example: myapp: //), the application starts.

If I want to process the URL, I found the following steps:

@interface EventHandler : NSObject { } @end @implementation EventHandler - (id)init { self = [super init]; if (self) { NSLog(@"eventHandler::init"); NSNotificationCenter* defaultCenter = [NSNotificationCenter defaultCenter]; [defaultCenter addObserver:self selector:@selector(applicationDidFinishLaunching:) // name:NSApplicationWillFinishLaunchingNotification name:NSApplicationDidFinishLaunchingNotification object:nil]; } return self; } - (void)applicationDidFinishLaunching:(NSNotification *)aNotification { NSAppleEventManager *appleEventManager = [NSAppleEventManager sharedAppleEventManager]; [appleEventManager setEventHandler:self andSelector:@selector(handleGetURLEvent:withReplyEvent:) forEventClass:kInternetEventClass andEventID:kAEGetURL]; } - (void)handleGetURLEvent:(NSAppleEventDescriptor *)event withReplyEvent:(NSAppleEventDescriptor *)replyEvent { NSString* url = [[event paramDescriptorForKeyword:keyDirectObject] stringValue]; NSLog(@"%@", url); } @end 

The above code works if the application is running, but if the URL is called and the application has been terminated, the event will not be detected. I think this is because it is: NSApplicationDidFinishLaunchingNotification. Changing it to NSApplicationWillFinishLaunchingNotification causes non-events to be caught. Qt may be handling it in front of me, but I cannot find a workaround for the problem.

Answer 1

I also tried to get my Qt-based application to handle a custom URL scheme on a Mac and go the same way as the original poster. It turns out that Qt4 already supports URL events on Mac, and there is no need to write Objective-C code to receive them. This is essentially the reason that you did not receive any URL events when you set up an event handler in response to NSApplicationWillFinishLaunchingNotification: Qt then registers its own handler.

When the URL with your custom schema starts, your Qt application will receive a FileOpenEvent file. Note that the QApplication instance accepts the event. You can catch it by subclassing the QApplication application or by setting an event filter in standard QApplication. I chose this second approach.

Here's the eventFilter method of my custom event filter class, FileOpenEventFilter. It just emits a urlOpened signal when the event contains a non-empty URL. It also saves the last open URL if my main window is not fully initialized when an event arrives (which happens in my application when it is not already running when I click on a custom URL).

 bool FileOpenEventFilter::eventFilter(QObject* obj, QEvent* event) { if (event->type() == QEvent::FileOpen) { QFileOpenEvent* fileEvent = static_cast<QFileOpenEvent*>(event); if (!fileEvent->url().isEmpty()) { m_lastUrl = fileEvent->url().toString(); emit urlOpened(m_lastUrl); } else if (!fileEvent->file().isEmpty()) { emit fileOpened(fileEvent->file()); } return false; } else { // standard event processing return QObject::eventFilter(obj, event); } } 

Answer 2

I register the handler in the delegate method of my application applicationWillFinishLaunching: and I do not miss any events. You are probably initializing your EventHandler object too late to receive this notification. If you want to save it as a separate class, that’s fine, but you have to create your object and register it using NSAppleEventManager in the applicationWillFinishLaunching: method of your application delegate.