UIImagePickerController在iPhone和iPad中用法的一点不同

我们知道，在iPhone中获取照片库常用的方法如下：

UIImagePickerController *m_imagePicker = [[UIImagePickerController alloc] init];

    if ([UIImagePickerController isSourceTypeAvailable:

         UIImagePickerControllerSourceTypePhotoLibrary]) {

        m_imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;

        m_imagePicker.delegate = self;

        //        [m_imagePicker.navigationBar.subviews];

        [m_imagePicker setAllowsEditing:NO];

        //m_imagePicker.allowsImageEditing = NO;

        [self presentModalViewController:m_imagePicker animated:YES];

        [m_imagePicker release];

    }else {

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

        [alert show];

        [alert release];

    }

这对iPhone的操作是没有问题的。但是当我们在iPad环境中却有问题了，当我们运行时会报如下错误：

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'On iPad, UIImagePickerController must be presented via UIPopoverController'

所以我们必须通过UIPopoverController来实现才行。具体实现如下：

UIImagePickerController *m_imagePicker = [[UIImagePickerController alloc] init];

    if ([UIImagePickerController isSourceTypeAvailable:

         UIImagePickerControllerSourceTypePhotoLibrary]) {

        m_imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;

        m_imagePicker.delegate = self;

        [m_imagePicker setAllowsEditing:NO];

        UIPopoverController *popover = [[UIPopoverController alloc] initWithContentViewController:m_imagePicker];

        self.popoverController = popover;

        //popoverController.delegate = self;

        

        [popoverController presentPopoverFromRect:CGRectMake(0, 0, 300, 300) inView:self.view permittedArrowDirections:UIPopoverArrowDirectionAny animated:YES];

        

        //[self presentModalViewController:m_imagePicker animated:YES];

        [popover release];

        [m_imagePicker release];

    }else {

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

        [alert show];

        [alert release];

    }

这里需要注意，对局部UIPopoverController对象popover我们赋给了一个全局的UIPopoverController对象popoverController。而不能直接调用popover。因为在popover对象还可见时，是不能够被释放的。

转载：http://huchenqiang90.blog.163.com/blog/static/1125008002011018416051/