UIImagePickerController在iPhone和iPad上的区别

在iPhone中获取照片库的常用方法如下：

 

UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
if ([UIImagePickerController isSourceTypeAvailable:
		 UIImagePickerControllerSourceTypePhotoLibrary]) {
	imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
	imagePicker.delegate = self;
	[imagePicker setAllowsEditing:NO];
	[self presentModalViewController:imagePicker animated:YES];
	[imagePicker release];
} else {
	UIAlertView *alert = [[UIAlertView alloc]initWithTitle:nil message:@"Error accessing photo library!" delegate:nil cancelButtonTitle:@"Close" otherButtonTitles:nil];
	[alert show];
	[alert release];
}

 

这在iPhone下操作是没有问题的，但在iPad下就会有问题了，运行时会报出下面的错误：

 

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。具体的实现如下：

 

UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
if ([UIImagePickerController isSourceTypeAvailable:
		 UIImagePickerControllerSourceTypePhotoLibrary]) {
	imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
	imagePicker.delegate = self;
	[imagePicker setAllowsEditing:NO];
	UIPopoverController *popover = [[UIPopoverController alloc] initWithContentViewController:imagePicker];
	self.popoverController = popover;
	[popoverController presentPopoverFromRect:CGRectMake(0, 0, 300, 300) inView:self.view permittedArrowDirections:UIPopoverArrowDirectionAny animated:YES];
	[popover release];
	[imagePicker release];
} else {
	UIAlertView *alert = [[UIAlertView alloc]initWithTitle:nil message:@"Error accessing photo library!" delegate:nil cancelButtonTitle:@"Close" otherButtonTitles:nil];
	[alert show];
	[alert release];
}