Introduction to Objective-Cand Xcode (Part 5)

FA 175Intro 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-fo

r-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 AudioToolbox library

Setting up and playing sounds

• Set up– Define sound id

• SystemSoundId _soundId;

– Specify sound file• NSString *file = [[NSBundle mainBundle] 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 propertyself.imageView.image =

[UIImage imageNamed:@"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 = [NSArray arrayWithObjects: [UIImage imageNamed:@"x.jpeg"], [UIImage imageNamed:@"y.jpeg"], [UIImage imageNamed:@"z.jpeg"], nil]; self.iv.animationImages = images; self.iv.animationDuration = 0.5; [self.iv startAnimating];

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