C/C++ (iOS) - API Bindings

Objective-C is compatible to C. This allows to use the C/C++ bindings in an iOS App. For general information see the documentation about the C/C++ bindings, this page only covers iOS specific things.

In the following we assume that you already have the iOS development environment installed.

Testing an Example

As an example we will create a small project that can toggle a Dual Relay Bricklet. It should be easy to adjust this example for your needs.

Start a new Xcode project by clicking on:

  • File
  • New
  • Project...
  • Choose "iOS Application"
  • Choose "Single View Application"
  • Click Next
  • Choose a "Product Name" (e.g. Relay)
  • Click Next
  • Choose a "Folder" for the project
  • Click Create

Add the C/C++ bindings code:

  • Right click on the Relay folder in the Project navigator
  • New Group, choose name "Tinkerforge"
  • Right click on new Tinkerforge group
  • Add Files to "Relay"...
  • Choose all files from the source/ folder of the C/C++ bindings

Below is a small example program that turns a relay on and off with a toggle button.

Edit AppDelegate.h as shown below and add the two variables for the IPConnection and DualRelay objects and the toggleRelays Interface Builder action.

#import <UIKit/UIKit.h>
#include "ip_connection.h"
#include "bricklet_dual_relay.h"

@interface AppDelegate : UIResponder <UIApplicationDelegate>
    IPConnection ipcon;
    DualRelay dr;

@property (strong, nonatomic) UIWindow *window;

- (IBAction)toggleRelays;


Edit AppDelegate.m as shown below to create the IPConnection and DualRelay objects after the App is launched. For simplicity no error handling is done here. In the toggleRelays action the state of both relays is switched.

#import "AppDelegate.h"

@implementation AppDelegate

@synthesize window = _window;

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
    // Change to the IP address of your host
    dual_relay_create(&dr, "XYZ", &ipcon); // Change XYZ to the UID of your Dual Relay Bricklet
    ipcon_connect(&ipcon, "", 4223);
    dual_relay_set_state(&dr, true, true);

    return YES;

- (IBAction) toggleRelays
    // Get state of both relays and toogle it
    bool state1, state2;
    dual_relay_get_state(&dr, &state1, &state2);
    dual_relay_set_state(&dr, !state1, !state2);


Now open MainStoryboard.storyboard in the Interface Builder and add a Label and a on/off Switch object as shown in the screenshot. The last step is to connect the Switch Value Changed event with the toggleRelays action:

  • Right click on the Switch
  • Click on the circle right of the Value Changed event
  • Drag a line to the First Responder
  • Choose toogleRelays from the action menu
Xcode example for C/C++ bindings in iOS
Xcode example for C/C++ bindings in iOS, connect event (step 1) Xcode example for C/C++ bindings in iOS, connect event (step 2)

Test the App in the simulator by clicking the Run button. Don't forget to change the UID and the host IP address to the correct values for your brickd host and your Dual Relay Bricklet.