Introduction to Objective-C and Xcode (Part 5)

Introduction to Objective-Cand Xcode (Part 5) FA 175 Intro to Mobile App Development

Agenda • Sounds • System Sound Services • Images • Image View and the UIImage class

Sounds • Reference: • http://www.raywenderlich.com/259/audio-101-for-iphone-developers-playing-audio-programmatically • Various ways to play sound, depending on format, length, and whether you want sounds played in the background • For this class, we will use System Sound Services via the AudioToolboxlibrary

Setting up and playing sounds • Set up • Define sound id • SystemSoundId _soundId; • Specify sound file • NSString *file = [[NSBundlemainBundle] pathForResource: @"soundfile" ofType:@"wav"]; • NSURL *url =[NSURL fileURLWithPath:file]; • Associate with sound id • AudioServicesCreateSystemSoundID((CFURLRef) url, &_soundId); • Play • Play by indicating sound id • AudioServicesPlaySystemSound(_soundId);

Sounds class • Create a Sounds class that “houses” sound-related functions • Methods: • prepSounds: setup the different sounds to be used by application (executes automatically through load method) • playSoundname: for each of the sound • Make sure to • Include AudioToolbox library in frameworks • Include sound files in “Supporting Files” • Make the library and files part of project target

Sounds class (version 2) • More flexible: allows adding of sound files from outside of the Sounds class • For the first version, you would need to update the Sounds class for every application • Methods: • prepSounds: setup the sound ids (array) • setSound: associate file to an idNum (int) • play: plays the sound by indicating the idNum

Class methods revisited • Take note: the methods of the Sounds class are class methods • .h file (interface) contains method declarations with the + prefix • When using the class, [Sounds <method>]; • e.g.,[Sounds playWoosh]; // version 1[Sounds setSound: 3: @"file”: @"wav"]; // ver 2[Sounds play: 3]; // ver 2

Images • Image View • Displays an image or animation (described by several images) • Placed within a UI View of a View Controller • Associated image can be assigned either • Through the Xcode environment: through attributes inspector • Or programmatically, by setting properties or calling methods on the UIImageView outlet connection

UIImage • Set image of image view by assigning a UIImage object to the view’s image property self.imageView.image = [UIImageimageNamed:@"x.jpg"]; • Make sure all image files needed are included in the “Supporting Files” area (and added to the project’s target

Animation • Set up an NSArray of images representing the images describing the animation • Set two properties of the view • animationImages: the NSArray • animationDuration: number representing the duration (in seconds) for one animation cycle • Call startAnimating method on the view

Animation Example NSArray *images = [NSArrayarrayWithObjects: [UIImageimageNamed:@"x.jpeg"], [UIImageimageNamed:@"y.jpeg"], [UIImageimageNamed:@"z.jpeg"], nil]; self.iv.animationImages = images; self.iv.animationDuration = 0.5; [self.ivstartAnimating];

Exercise • Create a single view project with three buttons and one image view • Set the image of the view to some default image • Button 1: changes the image the another image • Button 2: plays a sound • Button 3: plays a different sound and then runs an animation • The project requires 2 sounds and at least 4 images

Summary • Sounds in an app can be played throughSystems Sound Services using the AudioToolbox library • Other frameworks are available • A Sounds class supporting sound support has been created for this course to simplify use • Images and animation supported through • UIImageView class • UIImage class

Introduction to Objective-C and Xcode (Part 5)