Sounds, Images, and Text

1. Sounds, Images, and Text FA 172 Intro to Mobile App Development

2. Agenda • Sounds • System Sound Services • Images • Image View and the UIImageclass • Text • Files, parsing, Web access

3. 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

4. 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);

5. Sounds class • A Sounds class (Sounds.h, Sounds.m) has been provided that enables sound support • You are welcome to look at the implementation but do not need to as long as you understand how to invoke the methods • Class methods: • setSound: associate a sound file to an idNum (int) • play: plays the sound by indicating the idNum • Make sure to • Include AudioToolbox library in frameworks(Build Phases, Link Binary with Libraries) • Include sound files in “Supporting Files”

6. 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 setSound: 3: @"file”: @"wav"];[Sounds play: 3];

7. 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

8. 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

9. 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 • Call stopAnimating method to stop animation

10. 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];

11. 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 to 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

12. Text • Demonstrated through a sample project • Text files: read/write text (NSString*) from/to files • Parsing: from NSString to NSArray • Reading data from the web • To be posted on the website

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