GSEvent
GSEvent is a group of C functions located in GraphicsServices.framework that passes hardware events around the system. GSEvent is a core part of UIEvent, which is simply a wrapper around GSEvent.
GSEvents are sent using Mach messages. A basic event consists of the following information:
- The type of event.
- Location and time of the event.
- Which process sent the event.
- Which window should receive the event.
Event types
Some events can be used only for SpringBoard. They will usually become no-op when sent to non-SpringBoard apps. Note that some sensor events like the gyroscope and magnetometer are processed in CoreMotion by directly communicating with the HID subsystem, instead of via the slower GSEvent system.
| type | name |
|---|---|
| 2000 | Launch |
| 2013 | ? |
| 2001 | Another application finished launching |
| 2002 | ? |
| 2012 | Imminent process assertion expiration |
| 2003 | Resume |
| 2014 | Start running in task switcher and deactivate |
| 2015 | Stop running in task switcher and activate |
| 2006 | Handle test URL |
| 2004 | Did end resume animation |
| 2005 | Will begin suspend animation |
| 2007 | Suspend, events only |
| 2008 | Suspend |
| 2009 | Exit |
| 2011 | Suspend settings updated |
| 12 | Modifier changed |
| 1012 | Ringer off |
| 1013 | Ringer on |
| 4001 | Accessory key state changed |
| 1022 | Media key up |
| 1023 | Media key down |
| 1014 | Lock device |
| 2010 | Quit top application |
| 500 | Dump UI hierarchy |
| 501 | Dump screen contents |
| 200 | Process script |
| 1100 | Vibrate |
| 1103 | Set backlight level |
| 23 | Accelerometer event |
| 50 | Device orientation changed |
| 24 | Proximity state changed |
| 6000 | Urgent memory warning |
| 1024 | Status bar tapped |
| 100 | Reset idle timer and undim |
| 60 | App preference changed |
| 1000 | Menu button down |
| 1001 | Menu button up |
| 1010 | Lock button down |
| 1011 | Lock button up |
| 1018 | Headset button down |
| 1019 | Headset button up |
| 1021 | Headset availability changed |
| 14 | Hardware key down? |
| 1020 | Shake motion event |
| 13 | Simulator key down |
| 22 | Scroll wheel |
| 3001 | Hand event (i.e. touch-screen event) |
| 10 | Key down |
| 11 | Key up |
| 1006 | Volume Upper button down |
| 1007 | Volume Upper button up |
| 1008 | Volume Lower button down |
| 1009 | Volume Lower button up |
| 1015 | Status bar mouse down |
| 1016 | Status bar mouse dragged |
| 1017 | Status bar mouse up |
| 1102 | Set backlight factor |
| 4000 | Accessory availability changed |
| 4002 | ? |
| 5000 | Out-of-line data request |
| 5001 | Out-of-line data response |
Sending a GSEvent
In order to send a GSEvent, one must first create a struct consisting of a GSEventRecord followed by the actual event data. Below is an example of creating and sending an orientation event to a specific process.
struct GSOrientationEvent {
GSEventRecord record;
GSDeviceOrientationInfo orientationInfo;
} event; //Declare the struct containing the GSEventRecord and the event info
event.record.type = kGSEventDeviceOrientationChanged; //Set the event record's type.
event.record.timestamp = mach_absolute_time(); //Set the timestamp.
event.record.senderPID = getpid();//Set the record's sender PID.
event.record.infoSize = sizeof(GSDeviceOrientationInfo); //Set the size of the event info (the size of the data following the GSEventRecord)
event.orientationInfo.orientation = UIInterfaceOrientationPortrait; //Set the orientation info to the orientation wanted.
SBApplication *safari = [[SBApplicationController sharedInstance] applicationWithDisplayIdentifier:@"com.apple.mobilesafari"];
GSSendEvent((GSEventRecord*)event, (mach_port_t)[safari eventPort]); //Send the GSEvent to Safari's event port.
Purple system event port
The "Purple system event port" is the Mach port that receives system events (e.g. kGSEventLockDevice). This port is registered whenever the --RegisterForSystemEvents flag is provided to a UIKit application, or it is the first application that registers the com.apple.eventpump service for bootstrap lookup. In other words, these system events are directed to SpringBoard.
