//
// CameraViewController.m
// Camera
//
// Created by Dave Mark on 12/16/10.
// Copyright 2010 __MyCompanyName__. All rights reserved.
//

#import "CameraViewController.h"
#import <MobileCoreServices/UTCoreTypes.h>

@interface CameraViewController ()
static UIImage *shrinkImage(UIImage *original, CGSize size);
- (void)updateDisplay;
- (void)getMediaFromSource:(UIImagePickerControllerSourceType)sourceType;
@end

@implementation CameraViewController
@synthesize imageView;
@synthesize takePictureButton;
@synthesize moviePlayerController;
@synthesize image;
@synthesize movieURL;
@synthesize lastChosenMediaType;

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

- (void)viewDidAppear:(BOOL)animated {
[super viewDidAppear:animated];
[self updateDisplay];
}

- (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.
}

- (void)viewDidUnload {
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;
self.imageView = nil;
self.takePictureButton = nil;
self.moviePlayerController = nil;
[super viewDidUnload];
}

- (void)dealloc {
[imageView release];
[takePictureButton release];
[moviePlayerController release];
[image release];
[movieURL release];
[lastChosenMediaType release];
[super dealloc];
}

- (IBAction)shootPictureOrVideo:(id)sender {
[self getMediaFromSource:UIImagePickerControllerSourceTypeCamera];
}

- (IBAction)selectExistingPictureOrVideo:(id)sender {
[self getMediaFromSource:UIImagePickerControllerSourceTypePhotoLibrary];
}

#pragma mark UIImagePickerController delegate methods
- (void)imagePickerController:(UIImagePickerController *)picker 
didFinishPickingMediaWithInfo:(NSDictionary *)info {
self.lastChosenMediaType = [info objectForKey:UIImagePickerControllerMediaType];
if ([lastChosenMediaType isEqual:(NSString *)kUTTypeImage]) {
UIImage *chosenImage = [info objectForKey:UIImagePickerControllerEditedImage];
UIImage *shrunkenImage = shrinkImage(chosenImage, imageFrame.size);
self.image = shrunkenImage;
} else if ([lastChosenMediaType isEqual:(NSString *)kUTTypeMovie]) {
self.movieURL = [info objectForKey:UIImagePickerControllerMediaURL];
}
[picker dismissModalViewControllerAnimated:YES];
}

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

#pragma mark -
static UIImage *shrinkImage(UIImage *original, CGSize size) {
CGFloat scale = [UIScreen mainScreen].scale;
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();

CGContextRef context = CGBitmapContextCreate(NULL, size.width * scale,
size.height * scale, 8, 0, colorSpace, kCGImageAlphaPremultipliedFirst);
CGContextDrawImage(context,
CGRectMake(0, 0, size.width * scale, size.height * scale),
original.CGImage);
CGImageRef shrunken = CGBitmapContextCreateImage(context);
UIImage *final = [UIImage imageWithCGImage:shrunken];

CGContextRelease(context);
CGImageRelease(shrunken); 

return final;
}

- (void)updateDisplay {
if ([lastChosenMediaType isEqual:(NSString *)kUTTypeImage]) {
imageView.image = image;
imageView.hidden = NO;
moviePlayerController.view.hidden = YES;
} else if ([lastChosenMediaType isEqual:(NSString *)kUTTypeMovie]) {
[self.moviePlayerController.view removeFromSuperview];
self.moviePlayerController = [[[MPMoviePlayerController alloc]
initWithContentURL:movieURL] autorelease];
moviePlayerController.view.frame = imageFrame;
moviePlayerController.view.clipsToBounds = YES;
[self.view addSubview:moviePlayerController.view];
imageView.hidden = YES;
}
}

- (void)getMediaFromSource:(UIImagePickerControllerSourceType)sourceType {
NSArray *mediaTypes = [UIImagePickerController
availableMediaTypesForSourceType:sourceType];
if ([UIImagePickerController isSourceTypeAvailable:
sourceType] && [mediaTypes count] > 0) {
NSArray *mediaTypes = [UIImagePickerController
availableMediaTypesForSourceType:sourceType];
UIImagePickerController *picker =
[[UIImagePickerController alloc] init];
picker.mediaTypes = mediaTypes;
picker.delegate = self;
picker.allowsEditing = YES;
picker.sourceType = sourceType;
[self presentModalViewController:picker animated:YES];
[picker release];
}
else {
UIAlertView *alert = [[UIAlertView alloc] 
initWithTitle:@"Error accessing media" 
message:@"Device doesn’t support that media source." 
delegate:nil 
cancelButtonTitle:@"Drat!" 
otherButtonTitles:nil];
[alert show];
[alert release];
}
}

本文转自博客园知识天地的博客，原文链接：ios调用摄像头，如需转载请自行联系原博主。