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Phidget22 API (select C from the drop-down menu)

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Getting Started with Swift

Welcome to using Phidgets with Swift! By using Swift, you will have access to the complete Phidget22 API, including events. We also provide example code in Swift for multiple Phidget classes.

iOS

If you haven't already, please visit the iOS page before you continue reading. There you will be instructed on how to properly set up your development machine so you can follow the guides below!

Xcode

Use Our Examples

One of the best ways to start programming with Phidgets is to use our example code as a guide. In order to run the examples for iOS you will need to download Xcode from the Mac App Store.

You will also need to install CocoaPods in order to access the Phidget libraries for Swift. You can do this by opening the terminal and entering the following command:

sudo gem install cocoapods

Now that you have Xcode and CocoaPods installed, download a Swift example that will work with your Phidget:

Swift Examples

After opening the example, you will notice that there is a file called Podfile

If you open this file, you can see that there is a reference to the Phidget22Swift pod. Note that no version number is included, so the newest available version of the Phidget22Swift pod will be installed:

To install the Phidget libraries, open a terminal at the example location and enter the following command:

pod install

After the libraries are installed, open the .xcworkspace file:

Next simply select the type of device you would like the application to run on and press play:

Here is an example output:

Configure Your Project

Whether you are building a project from scratch, or adding Phidget functionality to an existing project, you will need to configure your development environment to properly link the Phidget libraries. To begin:

Create a new Xcode project:

Next, select an iOS application. For this tutorial's purposes, we will use a Single View Application:

Name the project, select Swift as the language, and choose which devices will be supported:

Now that your project is created, you need to add the Phidget libraries. In order to do this, you must have CocoaPods installed on your computer (this is covered in detail above in the use our examples section). Open a terminal at the example location and enter the following command:

pod init

This will create a new Podfile. Open the Podfile in your favorite text editor and add a reference to the Phidget22Swift pod:

Save your edit to the Podfile, and then enter the following command in the terminal which was opened at the example location:

pod install

After running the command, open the xcworkspace file and access the Phidget libraries by adding the following line to the top of your files:

import Phidget22Swift

Success! The project now has access to Phidgets and we are ready to begin coding.

Write Code

By following the instructions for your operating system and compiler above, you now have working examples and a project that is configured. This teaching section will help you understand how the examples were written so you can start writing your own code.

Remember: your main reference for writing Swift code will be the Phidget22 API Manual and the example code.

Step One: Initialize and Open

You will need to declare your Phidget object in your code. For example, we can declare a digital input object like this:

let ch = DigitalInput()

Next, the Phidget object needs to be opened:

ch.open()

Although we are not including it on this page, you need to include error handling for all Phidget functions. Here is an example of the previous code with error handling:

do{
  try ch.open
}catch let error as PhidgetError{
  //handle error
}

Step Two: Wait for Attachment (Plugging In) of the Phidget

Simply calling open does not guarantee you can use the Phidget immediately. To use a Phidget, it must be plugged in (attached). We can handle this by using event driven programming and tracking the attach events. Alternatively, we can modify our code so we wait for an attachment:

ch.open(timeout: 5000)

Waiting for attachment will block indefinitely until a connection is made, or until the timeout value is exceeded.

To use events, we have to modify our code slightly:

ch.attach.addHandler(attach_handler)
Phidget_open(ch)

Next, we have to declare the function that will be called when an attach event is fired - in this case the function attach_handler will be called.

func attach_handler(sender: Phidget){
  let attachedDevice = sender as! DigitalInput
  //configure device here
}

Step Three: Do Things with the Phidget

We recommend the use of event driven programming when working with Phidgets. In a similar way to handling an attach event as described above, we can also add an event handler for a state change event:

ch.attach.addHandler(attach_handler)
ch.stateChange.addhandler(stateChange_handler)
ch.open()

This code will connect a function and an event. In this case, the stateChange_handler function will be called when there has been a change to the devices input. Next, we need to create the stateChange_handler function:

func stateChange_handler(sender: DigitalInput, state: Bool){
  if(state){
    //state is true
  }
  else{
    //State is false
  }
}

If events do not suit your needs, you can also poll the device directly for data using code like this:

var state = ch.getState()
stateLabel.text = state ? "True" : "False"

Step Four: Close

At the end of your program, be sure to close your device.

ch.close()

@@ Line 111: / Line 111: @@
 {{WriteCode_Intro|Swift}}
-(Use the C API as a reference when using Swift)
 === Step One: Initialize and Open ===
 You will need to declare your Phidget object in your code. For example, we can declare a digital input object like this:
 <syntaxhighlight lang="swift">
-var ch:PhidgetDigitalInput? = nil
+let ch = DigitalInput()
 </syntaxhighlight>
-Next, the Phidget object needs to be initialized and opened:
+Next, the Phidget object needs to be opened:
 <syntaxhighlight lang="swift">
-PhidgetDigitalInput_create(&ch)
+ch.open()
-Phidget_open(ch)
 </syntaxhighlight>
-Although we are not including it on this page, you should include error handling for all Phidget functions. Here is an example of the previous code with error handling:
+Although we are not including it on this page, you need to include error handling for all Phidget functions. Here is an example of the previous code with error handling:
 <syntaxhighlight lang="swift">
-var res:PhidgetReturnCode = EPHIDGET_OK
+do{
+  try ch.open
-res = PhidgetDigitalInput_create(&ch)
+}catch let error as PhidgetError{
-if(res != EPHIDGET_OK){
+   //handle error
-   NSLog("Error")
 }
-res = Phidget_open(ch)
-if(res != EPHIDGET_OK){
-  NSLog("Error")
-}
-Phidget_open(ch)
 </syntaxhighlight>
 === Step Two: Wait for Attachment (Plugging In) of the Phidget ===
 Simply calling open does not guarantee you can use the Phidget immediately. To use a Phidget, it must be plugged in (attached). We can handle this by using event driven programming and tracking the attach events. Alternatively, we can modify our code so we wait for an attachment:
 <syntaxhighlight lang="swift">
-PhidgetDigitalInput_create(&ch)
+ch.open(timeout: 5000)
-Phidget_openWaitForAttachment(ch, 5000)
 </syntaxhighlight>
 Waiting for attachment will block indefinitely until a connection is made, or until the timeout value is exceeded.
@@ Line 154: / Line 143: @@
 To use events, we have to modify our code slightly:
 <syntaxhighlight lang="swift">
-PhidgetDigitalInput_create(&ch)
+ch.attach.addHandler(attach_handler)
-Phidget_setOnAttachHandler(ch, gotAttach, bridge(self))
 Phidget_open(ch)
 </syntaxhighlight>
-Next, we have to declare the function that will be called when an attach event is fired - in this case the function ''gotAttach'' will be called.
+Next, we have to declare the function that will be called when an attach event is fired - in this case the function ''attach_handler'' will be called.
 <syntaxhighlight lang="swift">
-let gotAttach: @convention(c)(PhidgetHandle?, UnsafeMutableRawPointer?) -> () = {phid,context in
+func attach_handler(sender: Phidget){
-    DispatchQueue.main.async(execute: {
+  let attachedDevice = sender as! DigitalInput
-        let myObject = Unmanaged<YourViewController>.fromOpaque(context!).takeUnretainedValue()
+  //configure device here
-        myObject.onAttachHandler()
-    })
-}
-</syntaxhighlight>
-The bridge function mentioned above is described here:
-<syntaxhighlight lang="swift">
-func bridge<T : AnyObject>(_ obj : T) -> UnsafeMutableRawPointer {
-    return Unmanaged.passUnretained(obj).toOpaque()
 }
 </syntaxhighlight>
@@ Line 182: / Line 160: @@
 <syntaxhighlight lang="swift">
-PhidgetDigitalInput_create(&ch)
+ch.attach.addHandler(attach_handler)
-Phidget_setOnAttachHandler(ch, gotAttach, bridge(self))
+ch.stateChange.addhandler(stateChange_handler)
-PhidgetDigitalInput_setOnStateChangeHandler(ch, gotStateChange, bridge(self))
+ch.open()
-Phidget_open(ch)
 </syntaxhighlight>
-This code will connect a function and an event. In this case, the ''gotStateChange'' function will be called when there has been a change to the devices input. Next, we need to create the ''gotStateChange'' function:
+This code will connect a function and an event. In this case, the ''stateChange_handler'' function will be called when there has been a change to the devices input. Next, we need to create the ''stateChange_handler'' function:
 <syntaxhighlight lang="swift">
-let gotStateChange: @convention(c)(PhidgetDigitalInputHandle?, UnsafeMutableRawPointer?, CInt) -> () = {_,context,cState in
+func stateChange_handler(sender: DigitalInput, state: Bool){
-    var state:Int32 = cState
+  if(state){
-    DispatchQueue.main.async(execute: {
+     //state is true
-        let myObject = Unmanaged<YourViewController>.fromOpaque(context!).takeUnretainedValue()
+  }
-        myObject.onStateChangeHandler(state)
+  else{
-     })
+    //State is false
-}
+  }
-</syntaxhighlight>
-Above, the onStateChangeHandler method is invoked on the main thread. Event data is stored as an Int32.
-The method onStateChangeHandler is defined as follows:
-<syntaxhighlight lang="swift">
-func onStateChangeHandler(_ state:Int32){
-    if  state == 0{
-        stateLabel.text = "False"
-    }
-    else{
-        stateLabel.text = "True"
-    }
 }
 </syntaxhighlight>
@@ Line 217: / Line 180: @@
 If events do not suit your needs, you can also poll the device directly for data using code like this:
 <syntaxhighlight lang="swift">
-var state = 0
+var state = ch.getState()
-PhidgetDigitalOutput_getState(ch, &state)
 stateLabel.text = state ? "True" : "False"
 </syntaxhighlight>
-=== Step Four: Close and Delete ===
+=== Step Four: Close ===
 At the end of your program, be sure to close your device.
 <syntaxhighlight lang="swift">
-Phidget_close(ch)
+ch.close()
-PhidgetDigitalInput_delete(&ch)
 </syntaxhighlight>

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