Audio app

To play audio on the phone, we will need to import the AVFoundation to our XCode created project header.
We also need to drag our audio file, say an .mp3 into our resources folder.

Here is what our header file will look like:

#import <UIKit/UIKit.h>

#import <AVFoundation/AVFoundation.h>

@interface ViewController : UIViewController

@property (weak, nonatomic) IBOutlet UIButton *playButton;
@property (weak, nonatomic) IBOutlet UIButton *stopButton;
@property (strong, nonatomic) AVAudioPlayer *audioPlayer;

-(IBAction)play;
-(IBAction)stop;

@end

The Storyboard and Implementation

For the Storyboard we drag over two buttons and connect them up with the play and stop functions from the previous slide.

Finally, our implementation file looks like:

//
//  ViewController.m
//  AudioExample
//
//  Created by Chris Pollett on 11/24/14.
//  Copyright 2010 San Jose State University. All rights reserved.
//

#import "ViewController.h"

@implementation ViewController

- (void)viewDidLoad {
	[super viewDidLoad];
	
	// Get the file path to the song to play.
	NSString *filePath = [[NSBundle mainBundle] pathForResource:@"warworlds"
            ofType:@"mp3"];
	
	// Convert the file path to a URL.
	NSURL *fileURL = [[NSURL alloc] initFileURLWithPath:filePath];
	
	//Initialize the AVAudioPlayer.
	self.audioPlayer = [[AVAudioPlayer alloc]
	    initWithContentsOfURL:fileURL error:nil];
	
	// Preloads the buffer and prepares the audio for playing.
	[self.audioPlayer prepareToPlay];

	
}

-(IBAction)play {
	
	// Make sure the audio is at the start of the stream.
	self.audioPlayer.currentTime = 0;
	
	[self.audioPlayer play];
	
}

-(IBAction)stop {
	
	[self.audioPlayer stop];
	
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end

Quiz

Which of the following is true?

A gesture event is always a single user touch of the screen by one finger followed by an immediate release.
If we handle both single and double taps then our code can detect immediately without a delay that only a single tap occurred.
An Android MediaPlayer object can be used to play an mp3.

VideoDemoViewController.m

A similar approach is used to play video.
We create a single-view app
We add fredott.m4v to the project making sure that it is added to the app target of the project.
We add MediaPlayer.framework to Linked Frameworks and Libraries.

The iPhone can be a little bit fussy about the video files it is willing to play:

//
//  ViewController.m
//  VideoDemo
//
//  Created by Chris Pollett on 11/24/14.
//  Copyright (c) 2014 Chris Pollett. All rights reserved.
//

#import "ViewController.h"
#import <MediaPlayer/MediaPlayer.h>

@interface ViewController () {
    MPMoviePlayerController *player;
}
@end

@implementation ViewController

- (void)viewDidLoad {

    NSString *url = [[NSBundle mainBundle]
                     pathForResource:@"fredott"
                     ofType:@"m4v"];
    player = [[MPMoviePlayerController alloc]
     initWithContentURL:[NSURL fileURLWithPath:url]];
    [player setControlStyle:MPMovieControlStyleFullscreen];
    [player setFullscreen:YES];
    [player prepareToPlay];

    [[NSNotificationCenter defaultCenter] addObserver:self
        selector:@selector(moviePlayerLoadStateChanged:)
        name:MPMoviePlayerLoadStateDidChangeNotification
        object:nil]; //this callback is called when video is load

    [[NSNotificationCenter defaultCenter]
     addObserver:self
     selector:@selector(movieFinishedCallback:)
     name:MPMoviePlayerPlaybackDidFinishNotification
     object:player]; // callback called when video is finished

    //---play movie---
    [super viewDidLoad];
}
- (void) moviePlayerLoadStateChanged:(NSNotification*)notification{
    if ([player loadState] != MPMovieLoadStateUnknown) {
        [[NSNotificationCenter defaultCenter] removeObserver:self
         name:MPMoviePlayerLoadStateDidChangeNotification
        object:nil];
        [player.view setFrame: self.view.bounds]; //here we play the video
        [self.view addSubview:player.view];
        [player play];
    }
}
- (void) movieFinishedCallback:(NSNotification*) aNotification {
    [[NSNotificationCenter defaultCenter]
     removeObserver:self
     name:MPMoviePlayerPlaybackDidFinishNotification
     object:player];
     NSLog(@"%f", player.currentPlaybackTime);
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end

Video Demo in Action

The Camera and Photo Library

iPhone applications are sandboxed.
Because of this, applications can't typically get to photographs or other data outside of their application.
Nevertheless, the camera and photo library are made available by way of an image picker.
This provides a mechanism that lets you select an image from a specified source.
Image pickers are implemented via a modal controller class called UIImagePickerController.
To create an instance of this class, you need to specify a delegate class, specify its image source, and then launch it modally,
The image picker will then take control of the iPhone to let the user select a picture or take it.
Regardless of whether an image is selected or cancelled, the delegate has the responsibility to dismiss the UIImagePickerController, so that the user can return to your app.
The possible source types for a UIImagePickerController are: UIImagePickerControllerSourceTypeCamera, UIImagePickerControllerSourceTypeSavedPhotosAlbum, UIImagePickerControllerSourceTypePhotoLibrary.
We will now create a small app to demo these things.

CameraIPhoneViewController.h



#import <UIKit/UIKit.h>

@interface CameraIPhoneViewController : UIViewController 
 <UIImagePickerControllerDelegate, UINavigationControllerDelegate> 
@property (nonatomic, weak) UIImageView *imageView;
@property (nonatomic, weak) UIButton *takePictureButton;
@property (nonatomic, weak) UIButton *selectFromCameraRollButton;
- (IBAction)getCameraPicture:(id)sender;
- (IBAction)selectExistingPicture;
@end

The Storyboard file

For the Soryboard file we drag over an image view to hold the camera scene, and we put three buttons beneath it.
We label these: Take New Picture, Pick from Camera Roll, and Pick From Library.
We hook up these buttons to the functions of the previous slide.

CameraIPhoneViewController.m


#import "CameraIPhoneViewController.h"

@implementation CameraIPhoneViewController

- (void)viewDidLoad {
   if(![UIImagePickerController 
		isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {
	   takePictureButton.hidden = YES;
	   selectFromCameraRollButton.hidden = YES;
   }
}

 // Override to allow orientations other than the default portrait orientation.
 - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
 // Return YES for supported orientations
 return (interfaceOrientation == UIInterfaceOrientationPortrait);
 }

- (void)didReceiveMemoryWarning {
	// Releases the view if it doesn't have a superview.
    [super didReceiveMemoryWarning];
	
	// Release any cached data, images, etc that aren't in use.
}


#pragma mark -
-(IBAction)getCameraPicture: (id)sender {
	UIImagePickerController *picker = [[UIImagePickerController alloc] init];
	picker.delegate = self;
	picker.allowsImageEditing = YES;
	picker.sourceType = (sender == takePictureButton) ?
		UIImagePickerControllerSourceTypeCamera :
		UIImagePickerControllerSourceTypeSavedPhotosAlbum;
	[self presentModalViewController:picker animated: YES];
}

-(IBAction)selectExistingPicture {
	if([UIImagePickerController isSourceTypeAvailable:
		UIImagePickerControllerSourceTypePhotoLibrary]) {
		UIImagePickerController *picker = 
			[[UIImagePickerController alloc] init];
		picker.delegate = self;
		picker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
		[self presentModalViewController:picker animated:YES];
	} else {
		UIAlertView *alert = [[UIAlertView alloc]
			initWithTitle:@"Error accessing photo library" 
			message:@"Device does not support a photo library" 
			delegate:nil 
			cancelButtonTitle:@"Darn!" 
							  otherButtonTitles:nil];
	}
}

-(void)imagePickerController:(UIImagePickerController *)picker
		didFinishPickingImage:(UIImage *)image
				 editingInfo:(NSDictionary *)editingInfo {
	imageView.image = image;
	UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil);
	[picker dismissModalViewControllerAnimated:YES];
}

-(void)imagePickerControllerDidCancel:(UIImagePickerController *)picker {
	[picker dismissModalViewControllerAnimated:YES];
}

@end

Multimedia on iPhone

Outline