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Subscribing to System Buttons

Subscribe buttons are used to detect changes to hard buttons located in the car's center console or steering wheel. You can subscribe to the following hard buttons:

Button Template Button Type
Play / Pause media template only soft button and hard button
Ok media template only soft button and hard button
Seek left media template only soft button and hard button
Seek right media template only soft button and hard button
Tune up media template only hard button
Tune down media template only hard button
Preset 0-9 any template hard button
Search any template hard button

Subscribe Buttons HMI

In the screenshot below, the pause, seek left and seek right icons are subscribe buttons.
Generic - Media Template with subscribe buttons


There is no way to customize a subscribe button's image or text.

The play/pause, seek left, seek right, tune up, and tune down subscribe buttons can only be used in the MEDIA template. Depending on the manufacturer of the head unit, the subscribe button might also show up as a soft button in the media template. For example, the SYNC 3 HMI will add the ok, seek right, and seek left soft buttons to the media template when you subscribe to those buttons. You will automatically be assigned the media template if you set your app's appType to MEDIA.


Before library v.6.1 and SDL Core v.5.0, Ok and PlayPause were combined into Ok. Subscribing to Ok will, in v.6.1, also subscribe you to PlayPause. This means that for the time being, you should not simultaneously subscribe to Ok and PlayPause. In a future major version, this will change. For now, only subscribe to either Ok or PlayPause and the library will execute the right action based on the version of Core to which you are connected.

SDLSubscribeButton *subscribeButton = [[SDLSubscribeButton alloc] initWithButtonName:SDLButtonNamePlayPause handler:^(SDLOnButtonPress * _Nullable buttonPress, SDLOnButtonEvent * _Nullable buttonEvent) {
    <#subscribe button selected#>
[manager sendRequest:subscribeButton withResponseHandler:^(__kindof SDLRPCRequest * _Nullable request, __kindof SDLRPCResponse * _Nullable response, NSError * _Nullable error) {
    if (error != nil) { return; }
    <#subscribe button sent successfully#>
let subscribeButton = SDLSubscribeButton(buttonName: .ok) { (buttonPress, buttonEvent) in
    <#subscribe button selected#>
sdlManager.send(request: subscribeButton) { (request, response, error) in
    guard error == nil else { return }
    <#subscribe button sent successfully#>
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