Template:PT3 SWIFT MAC XCODE 2

Language - Swift

Setting up a New 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:

Setting up a New Project

Next, select a macOS application:

Setting up a New Project

Name the project, select Swift as the language, and continue:

Setting up a New Project

Now that your project is created, you need to add the Phidget libraries (using CocoaPods). Open a terminal at the example location and enter the following command:

pod init

Setting up a New Project

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

Setting up a New Project

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

pod install

Setting up a New Project

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

You should now have working examples and a project that is configured. This next 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

● Swift example code

Write Code

Step One: Create And Address

First, create a Phidget object. For example, we can create a digital input object like this:

let ch = DigitalInput()

Next, we can address which Phidget we want to connect to by setting parameters such as DeviceSerialNumber.

ch.setDeviceSerialNumber(496911);

This guide won't go in-depth on error handling, but here is an example of the previous code with error handling:

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

Write Code

Step Two: Open And Wait For Attachment

After we have specified which Phidget to connect to, we can open the Phidget object like this:

ch.open(timeout: 5000)

To use a Phidget, it must be plugged in (attached). We can handle this by calling open(timeout), which will block until a connection is made, or until the timeout expires. Simply calling open() does not guarantee you can use the Phidget immediately.

Instead, you can verify the device is attached by using an attach handler. To use events to handle attachments, we have to modify our code slightly:

PhidgetDigitalInputHandle ch;
PhidgetDigitalInput_create(&ch);
ch.attach.addHandler(attach_handler)
Phidget_open(ch)

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Step Two: Open And Wait For Attachment

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

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

We recommend using this attach handler to set any initialization parameters for the channel such as DataInterval and ChangeTrigger from within the AttachHandler, so the parameters are set as soon as the device becomes available.

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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 to an event. In this case, the onStateChangeHandler function will be called when there has been a change to the channel's input.

Write Code

Step Three: Do Things With The Phidget

Next, we need to create the onStateChangeHandler function:

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

If you are using multiple Phidgets in your program, check out our page on Using Multiple Phidgets for information on how to properly address them and use them in events.

Write Code

Step Three: Do Things With The Phidget

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"

Important Note: There will be a period of time between the attachment of a Phidget sensor and the availability of the first data from the device. Any attempts to get this data before it is ready will result in an error code, and a specific nonsensical result. See more information on this on our page for Unknown Values.

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Step Three: Do Things With The Phidget

Some Phidget devices have functions that deal with specific predefined values called enumerations. Enumerations commonly provide readable names to a set of numbered options.

Enumerations with Phidgets in Swift will take the form of Phidget22Swift.EnumerationType.enumerationName.

For example, specifying a SensorType to use the 1142 for a voltage input would look like:

Phidget22Swift.VoltageSensorType.PN_1142

and specifying a K-Type thermocouple for a temperature sensor would be:

Phidget22Swift.ThermocoupleType.K

The Phidget error code for timing out could be specified as:

Phidget22Swift.ErrorCode.timeout

You can find the Enumeration Type under the Enumerations section of the Phidget22 API for your device, and the Enumeration Name in the drop-down list within.

Write Code

Step Four: Close

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

ch.close()

What's Next?

Now that you've set up Phidgets in your programming environment, you should read our guide on Phidget Programming Basics to learn the fundamentals of programming with Phidgets.

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