Initializing Input Servers

An input server is implemented as an NSInputServer object wrapped in a server application, which communicates via interprocess communication (IPC) with the current input manager. The input server must be initialized with its delegate (if a delegate is used) and an IPC connection name at runtime. The IPC connection name must match the one in the input server’s Info file (see Installing Input Servers.

The easiest way to do this is to perform the initialization in the application’s main() function—for example in the following code:

int main(int argc, const char *argv[])

{

    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

    [[NSInputServer alloc] initWithDelegate:[HexInputServer sharedInstance]

                           name:@"HexInputServer2ConnectionName"];

    [[NSApplication sharedApplication] run];

    [pool release];

    return 0;

}

Note that the HexInputServer class uses a sharedInstance method to create a HexInputServer object because only one such object will ever be created.

Installing Input Servers

An input server is installed as a directory hierarchy, which must be installed in ~/Library/InputManagers or /Library/InputManagers to be useful to users. At the top level of the hierarchy there is a text file called Info, an application bundle, and optionally a key-bindings dictionary file. The Info file contains a dictionary property list. When an application starts up, NSInputManager scans the InputManagers directories for input servers and uses the data from each folder’s Info file to create an input manager for its input server. If there are any custom input servers installed, an Input submenu appears in the Edit menu which lets the user switch between the different installed input servers. When the user chooses an input server, the input manager launches the input server if it’s not already running and connects to it via interprocess communication.

The Info file tells NSInputManager how to find the application executable, tells what the IPC connection name to use is, provides an optional key-bindings dictionary, and contains localized text strings to represent the input server in the Edit > Input submenu. The file can be an XML property list or an old-style ASCII property list, such as this example:

{

    // relative path to the executable to be launched

    ExecutableName = "HexInputServer.app/Contents/MacOS/HexInputServer";

    // The name registered with the IPC mechanism, the same as the one

    // used to initialize the NSInputServer object

    ConnectionName = "HexInputServer2ConnectionName";

    DisplayName = "Hexadecimal Input";

    DefaultKeyBindings = "HexInputServer.dict";

    // The name that will appear in the Edit > Input submenu

    LocalizedNames = { Deutsch = "Hexadezimaler Input"; }

    // Default name used for languages not found in LocalizedNames

    DisplayName = "Hexadecimal Input"

    // Optional. Returned by the current input manager’s language: method.

    LanguageName = "English";

    // Optional file to map keyboard characters to selector names

    DefaultKeyBindings = "HexInputServer.dict"

}

The DefaultKeyBindings file overrides the system’s default key-bindings file. (See About Key Bindings for more information.)

If you want to override the key-bindings mechanism entirely, make your input server’s wantsToInterpretAllKeystrokes method return YES.