在iOS设备（iPhone/iPad）中调用摄像头进行全屏拍摄时的处理方案

在实际开发中，UIImagePickerController的调用在iPhone和iPad的中是有些许差异的，因为两者设备间的固有的的差距，在iPhone中调用照片库中的图片可以直接进行

首先应当遵循UIImagePickerControllerDelegate协议

UIImagePickerController * picker = [[UIImagePickerController alloc]init];
if([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypePhotoLibrary]){
picker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
picker.delegate = self;
[picker setAllowsEditing:YES];

}else{
UIAlertView *alert = [[UIAlertView alloc]initWithTitle:nil message:@"Error accessing photo library!" delegate:nil cancelButtonTitle:@"Close" otherButtonTitles:nil];
[alert show];
[alert release];
}

调用即可

但是在iPad开发中由于屏幕大，如果是在一个小的View中调用需要遵循UIImagePickerControllerDelegate,UIPopoverControllerDelegate三个协议，并通过UIPopoverControllerView调用UIImagePickerControlle

UIImagePickerController * picker = [[UIImagePickerController alloc]init];
if([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypePhotoLibrary]){
picker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
picker.delegate = self;
[picker setAllowsEditing:YES];
UIPopoverController * popver = [[UIPopoverController alloc]initWithContentViewController:picker];
self.popverController = popver;
[self.popverController setPopoverContentSize:CGSizeMake(300, 500)];
[self.popverController presentPopoverFromRect:CGRectMake(103, 30, 59, 59) inView:self permittedArrowDirections:UIPopoverArrowDirectionAny animated:YES];
[popver release];
}
else{
UIAlertView *alert = [[UIAlertView alloc]initWithTitle:nil message:@"Error accessing photo library!" delegate:nil cancelButtonTitle:@"Close" otherButtonTitles:nil];
[alert show];
[alert release];
}

当需要调用摄像头时，如果需要的是非全屏的调用那么跟调用照片库的区别不大

//以浮动窗口的形式打开摄像头
if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {
UIImagePickerController * picker = [[UIImagePickerController alloc]init];
picker.delegate = self;
picker.sourceType = UIImagePickerControllerSourceTypeCamera;
picker.allowsEditing = YES;
picker.modalPresentationStyle = UIModalPresentationCurrentContext;
UIPopoverController * popver = [[UIPopoverController alloc]initWithContentViewController:picker];
self.popverController = popver;
picker.videoQuality = UIImagePickerControllerQualityTypeIFrame1280x720;
picker.cameraViewTransform = CGAffineTransformScale(picker.cameraViewTransform, 0.8, 1.0);
[self.popverController setPopoverContentSize:CGSizeMake(500, 800)];
[self.popverController presentPopoverFromRect:CGRectMake(103, 30, 59, 59) inView:self permittedArrowDirections:UIPopoverArrowDirectionAny animated:YES];
[popver release];
}else{

UIAlertView * alert = [[UIAlertView alloc]initWithTitle:@"错误" message:@"拍照功能暂时无法使用" delegate:nil cancelButtonTitle:@"确定" otherButtonTitles:nil, nil];
[alert show];
[alert release];
}

当然，如果大部分情况下使用摄像头进行拍摄时，都喜欢使用全屏，不但看起来比较酷，在苹果官方API中也是提倡的

首先，如果你调用摄像头的语句没有写在ViewController中，那么需要通过代理或者通知中心将事件转到ViewController中然后遵循UIImagePickerControllerDelegate,UINavigationControllerDelegate两个协议

#pragma mark - selectCamera
-(void)selectCamera{
[self startCameraControllerFromViewController: self
usingDelegate: self];
}

- (BOOL) startCameraControllerFromViewController: (UIViewController*) controller
usingDelegate: (id <UIImagePickerControllerDelegate,
UINavigationControllerDelegate>) delegate {

if (([UIImagePickerController isSourceTypeAvailable:
UIImagePickerControllerSourceTypeCamera] == NO)
|| (delegate == nil)
|| (controller == nil))
return NO;

UIImagePickerController *cameraUI = [[UIImagePickerController alloc] init];
cameraUI.sourceType = UIImagePickerControllerSourceTypeCamera;

// Displays a control that allows the user to choose picture or
// movie capture, if both are available:
cameraUI.mediaTypes =
[UIImagePickerController availableMediaTypesForSourceType:
UIImagePickerControllerSourceTypeCamera];

// Hides the controls for moving & scaling pictures, or for
// trimming movies. To instead show the controls, use YES.
cameraUI.allowsEditing = YES;

cameraUI.delegate = delegate;

[controller presentModalViewController: cameraUI animated: YES];
return YES;
}

同时应当事先协议中的两个函数

- (void) imagePickerControllerDidCancel: (UIImagePickerController *) picker {
//点击取消按钮时要实现的功能
[picker  dismissModalViewControllerAnimated: YES];
[picker release];
}
- (void) imagePickerController: (UIImagePickerController *) picker
didFinishPickingMediaWithInfo: (NSDictionary *) info {
}//点击选取的图片后应当实现的内容，info中包含有选取图片的内容，通过其中的内容可以获取选择的照片