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| [[Category:Language]]{{NoTitle}} | | #REDIRECT [[Language - Objective C]] |
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| |style="vertical-align:middle; width: 60%;"|
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| <font size=6>'''Language - Objective C'''
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| '''iOS with Xcode'''</font>
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| Welcome to using Phidgets with Objective C! By using Objective C, you will have access to the complete Phidget22 API, including events.
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| Xcode is an IDE provided by Apple that can be used to develop code in a wide variety of programming languages, including Objective C.
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| |{{TOC limit|2}}
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| |}
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| == Install Phidget Drivers for iOS ==
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| {{IOS_Languages}}
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| == Use Our Examples ==
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| 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 [https://developer.apple.com/xcode/ Xcode] from the Mac App Store.
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| Now that you have Xcode installed, download and unpack the Phidget libraries for iOS development. You will need to reference these files from your Xcode project in order to use Phidgets. This step is covered in detail below.
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| *[{{SERVER}}/downloads/phidget22/libraries/ios/Phidget22_iOS.zip Phidget iOS Libraries]
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| Next, download the Objective-C example:
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| *{{SampleCode|Objective-C|Objective-C Example}}
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| Unpack the Objective-C example and navigate to ''Phidget.xcodeproj''. Open the file in Xcode:
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| [[Image:Objectivec_open.png|link=|center]]
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| {{IOS_use_our_examples}}
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| ==Configure Your Project==
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| 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 library. To begin:
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| Create a new Xcode project:
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| [[Image:Cocoa_CreateProject.png |link=|center]]
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| Select an iOS application. For this tutorial's purposes, we will use a Single View Application:
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| [[Image:iOS_SingleView.png |link=|center]]
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| Name the project, select Objective-C as the language, and choose which devices will be supported:
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| [[Image:iOS_NameProject_objc.png|link=|center]]
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| Now that your project is created, you need to add references to the Phidget iOS libraries. This is covered in detail above in the [[#Use our examples |use our examples]] section.
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| After you have linked the Phidget iOS libraries, simply add a reference to phidget22.h in your header file:
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| <syntaxhighlight lang="objc">
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| #import "phidget22.h"
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| </syntaxhighlight>
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| Success! The project now has access to Phidgets and we are ready to begin coding.
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| == Write Code ==
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| {{WriteCode_Intro|Objective C|Objective-C}}
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| (Refer the the C API when using Objective C)
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| ==== Step One: Initialize and Open ====
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| You will need to declare your Phidget object in your code. For example, we can declare a digital input object like this:
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| <syntaxhighlight lang="objc">
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| PhidgetDigitalInput ch;
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| </syntaxhighlight>
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| Next, the Phidget object needs to be initialized and opened.
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| <syntaxhighlight lang="objc">
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| PhidgetDigitalInput_create(&ch);
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| Phidget_open((PhidgetHandle)ch);
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| </syntaxhighlight>
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| Although we are not including it on this page, you should handle the return values of all Phidget functions. Here is an example of the previous code with error handling:
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| <syntaxhighlight lang="objc">
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| PhidgetReturnCode res;
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| const char* errorString;
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| res = PhidgetDigitalInput_create(&ch);
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| if(res != EPHIDGET_OK){
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| Phidget_getErrorDescription ( returnValue, &errorString );
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| NSLog(@"Handle error here");
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| }
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| res = Phidget_open((PhidgetHandle)ch);
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| if(res != EPHIDGET_OK){
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| Phidget_getErrorDescription ( returnValue, &errorString );
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| NSLog(@"Handle error here");
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| }
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| </syntaxhighlight>
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| ==== Step Two: Wait for Attachment of the Phidget ====
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| 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:
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| <syntaxhighlight lang="objc">
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| PhidgetDigitalInput_create(&ch);
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| Phidget_openWaitForAttachment(ch, 5000);
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| </syntaxhighlight>
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| Waiting for attachment will block indefinitely until a connection is made, or until the timeout value is exceeded.
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| To use events to handle attachments, we have to modify our code slightly:
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| <syntaxhighlight lang="objc">
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| PhidgetDigitalInput_create(&ch);
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| Phidget_setOnAttachHandler((PhidgetHandle)ch,gotAttach,(__bridge void*)self);
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| Phidget_open((PhidgetHandle)ch);
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| </syntaxhighlight>
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| 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:
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| <syntaxhighlight lang="objc">
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| static void gotAttach(PhidgetHandle phid, void *context){
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| [(__bridge id)context performSelectorOnMainThread:@selector(deviceAttached)
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| withObject:nil
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| waitUntilDone:NO];
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| }
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| </syntaxhighlight>
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| ==== Step Three: Do Things with the Phidget ====
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| 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:
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| <syntaxhighlight lang="objc">
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| PhidgetDigitalInput_create(&ch);
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| Phidget_setOnAttachHandler((PhidgetHandle)ch,gotAttach,(__bridge void*)self);
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| PhidgetDigitalInput_setOnStateChangeHandler(ch, gotStateChange, (__bridge void*)self);
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| Phidget_open((PhidgetHandle)ch);
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| </syntaxhighlight>
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| 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.
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| <syntaxhighlight lang="objc">
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| void gotStateChange(PhidgetDigitalInputHandle phid, void *context, int state){
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| [(__bridge id)context performSelectorOnMainThread:@selector(onStateChangeHandler:)
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| withObject:[NSNumber numberWithInt:state]
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| waitUntilDone:NO];
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| }
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| </syntaxhighlight>
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| Above, the onStateChangeHandler method is invoked on the main thread. Event data is stored as an NSNumber.
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| The method ''onStateChangeHandler'' is defined as follows:
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| <syntaxhighlight lang="objc">
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| - (void)onStateChangeHandler:(NSNumber *)state{
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| if(state.intValue)
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| stateTextField.stringValue = @"True";
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| else
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| stateTextField.stringValue = @"False";
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| }
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| </syntaxhighlight>
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| If events do not suit your needs, you can also poll the device directly for data using code like this:
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| <syntaxhighlight lang="objc">
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| int state;
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| PhidgetDigitalInput_getState(ch, &state);
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| stateTextField.stringValue = [NSString stringWithFormat:@"%@", state ? @"True" : @"False"];
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| </syntaxhighlight>
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| ==== Step Four: Close and Delete ====
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| At the end of your program, be sure to close and delete your device:
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| <syntaxhighlight lang="objc">
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| Phidget_close((PhidgetHandle)ch);
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| PhidgetDigitalInput_delete(&ch);
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| </syntaxhighlight>
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| {{Language Page What's Next}}
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