On iPad, UIImagePickerController must be presented via UIPopoverController

本文转载至：http://blog.csdn.net/k12104/article/details/8537695

On iPad, UIImagePickerController must be presented via UIPopoverController  可以用以下方法来判断设备的类型选择不同的Controller

if(UI_USER_INTERFACE_IDIOM()==UIUserInterfaceIdiomPhone){// We are using an iPhoneUIActionSheet*alertSheet =[[UIActionSheet alloc] initWithTitle:@"Where do you want to get your daily image?" delegate:(self) cancelButtonTitle:@"Cancel" destructiveButtonTitle:nil otherButtonTitles:@"Camera",@"Library", nil];[alertSheet setTag:0];[alertSheet setDelegate:self];[alertSheet showFromTabBar:[[self tabBarController] tabBar]];[alertSheet release];}else{// We are using an iPadUIImagePickerController*imagePickerController =[[UIImagePickerController alloc] init];
    imagePickerController.delegate = self;UIPopoverController*popoverController=[[UIPopoverController alloc] initWithContentViewController:imagePickerController];
    popoverController.delegate=self;[popoverController presentPopoverFromRect:((UIButton*)sender).bounds inView:sender permittedArrowDirections:UIPopoverArrowDirectionAny animated:YES];}

iPad与iPhone调用UIImagePickerViewController方法略有不同是本文要介绍的内容，文中很详细的讲述了iPad与iphone各自的调用方法，来看详细内容。

我们知道，在iPhone中获取照片库常用的方法如下：

1. UIImagePickerController *m_imagePicker = [[UIImagePickerController alloc] init];
2. if ([UIImagePickerController isSourceTypeAvailable:
3. UIImagePickerControllerSourceTypePhotoLibrary]) {
4. m_imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
5. m_imagePicker.delegate = self;
6. //        [m_imagePicker.navigationBar.subviews];
7. [m_imagePicker setAllowsEditing:NO];
8. //m_imagePicker.allowsImageEditing = NO;
9. [self presentModalViewController:m_imagePicker animated:YES];
10. [m_imagePicker release];
11. }else {
12. UIAlertView *alert = [[UIAlertView alloc]initWithTitle:nil message:
13. @"Error accessing photo library!" delegate:nil cancelButtonTitle:@"Close" otherButtonTitles:nil];
14. [alert show];
15. [alert release];
16. }

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：

1. Terminating app due to uncaught exception 'NSInvalidArgumentException',
2. 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：

1. UIImagePickerController *m_imagePicker = [[UIImagePickerController alloc] init];
2. if ([UIImagePickerController isSourceTypeAvailable:
3. UIImagePickerControllerSourceTypePhotoLibrary]) {
4. m_imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
5. m_imagePicker.delegate = self;
6. [m_imagePicker setAllowsEditing:NO];
7. UIPopoverController *popover = [[UIPopoverController alloc] initWithContentViewController:m_imagePicker];
8. self.popoverController = popover;
9. //popoverController.delegate = self;
10. [popoverController presentPopoverFromRect:CGRectMake(0, 0, 300, 300) inView:self.
11. view permittedArrowDirections:UIPopoverArrowDirectionAny animated:YES];
12. //[self presentModalViewController:m_imagePicker animated:YES];
13. [popover release];
14. [m_imagePicker release];
15. }else {
16. UIAlertView *alert = [[UIAlertView alloc]initWithTitle:nil message:@"Error accessing photo library!"
17. delegate:nil cancelButtonTitle:@"Close" otherButtonTitles:nil];
18. [alert show];
19. [alert release];
20. }

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。

小结：iPad与iphone调用UIImagePickerViewController方法略有不同的内容介绍完了，希望本文对你有所帮助！