我正在尝试编写代码来从iPad上的照片库中选择图像。我正在使用的代码如下（取自Apple的网站），但它一直给我一个错误，说On iPad, UIImagePickerController must be presented via UIPopoverController。我已经尝试更改这一行：UIImagePickerController *mediaUI = [[UIImagePickerController alloc] init];使用UIPopoverController，但显然我做错了，因为它不起作用。
- (BOOL) selectImage: (UIViewController*) controller
usingDelegate: (id <UIImagePickerControllerDelegate,
UINavigationControllerDelegate>) delegate {
if (([UIImagePickerController isSourceTypeAvailable:
UIImagePickerControllerSourceTypeSavedPhotosAlbum] == NO)
|| (delegate == nil)
|| (controller == nil))
return NO;
UIImagePickerController *mediaUI = [[UIImagePickerController alloc] init];
mediaUI.sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum;
// Displays saved pictures and movies, if both are available, from the
// Camera Roll album.
mediaUI.mediaTypes =
[UIImagePickerController availableMediaTypesForSourceType:
UIImagePickerControllerSourceTypeSavedPhotosAlbum];
// Hides the controls for moving & scaling pictures, or for
// trimming movies. To instead show the controls, use YES.
mediaUI.allowsEditing = NO;
mediaUI.delegate = delegate;
[controller presentModalViewController: mediaUI animated: YES];
return YES; }
Apple Developer页面还说：“在iPad上，您可以使用initWithContentViewController中描述的弹出窗口以及UIPopoverController类参考中的”呈现和解除弹出窗口“来呈现浏览器界面。我已经读过了，但我仍然无法让它工作。任何帮助将不胜感激。
答案 0 :(得分：3)
这样的事情应该有效：
// create an image picker controller
UIImagePickerController *imagePickerController = [[[UIImagePickerController alloc] init] autorelease];
imagePickerController.sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum;
imagePickerController.delegate = self;
// present it in a popover
self.popoverController = [[[UIPopoverController alloc] initWithContentViewController:imagePickerController] autorelease];
self.popoverController.delegate = self;
// I was presenting the popover from a button, but you would set the rect to whatever is appropriate for your app
[self.popoverController presentPopoverFromRect:((UIButton *)sender).bounds inView:sender permittedArrowDirections:UIPopoverArrowDirectionAny animated:YES];
答案 1 :(得分：1)
声明如下的ivar：
UIPopoverController *imagePopover;
然后：
imagePopover = [[UIPopoverController alloc] initWithContentViewController:mediaUI];
[imagePopover setDelegate:self];
[imagePopover presentPopoverFromRect:someRect
inView:someView
permittedArrowDirections:UIPopoverArrowDirectionAny
animated:YES];
取代
[controller presentModal...];
答案 2 :(得分：1)
UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
imagePicker.delegate = self;
imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
popover = [[UIPopoverController alloc] initWithContentViewController:imagePicker];
[popover presentPopoverFromRect:CGRectMake(0.0, 0.0, 400.0, 400.0)
inView:self.view
permittedArrowDirections:UIPopoverArrowDirectionAny
animated:YES];
参考以下链接
答案 3 :(得分：1)
我经历了很多痛苦，提出了一个适用于iPad和iPhone的解决方案，这是最终的代码，其中一些来自其他人的评论： 代码有一些错误，但它是一个非常好的开始:) 它涵盖了所需的权限以及如何管理在ipad上弹出的viewcontrollers。
需要以下导入：
#import <AVFoundation/AVFoundation.h>
#import <AssetsLibrary/AssetsLibrary.h>
并添加此委托：
UIActionSheetDelegate, UIImagePickerControllerDelegate
定义：
__weak IBOutlet UIButton *attachButton;
UIImage *image;
按钮的操作：
- (IBAction)doAttach:(id)sender {
UIActionSheet *action = [[UIActionSheet alloc] initWithTitle:@"Select image from" delegate:self cancelButtonTitle:@"Cancel" destructiveButtonTitle:nil otherButtonTitles:@"From library",@"From camera", nil] ;
[action showInView:self.view];
}
#pragma mark - ActionSheet delegates
- (void)actionSheet:(UIActionSheet *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex
{
if( buttonIndex == 1 ) {
AVAuthorizationStatus authStatus = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeVideo];
if(authStatus == AVAuthorizationStatusAuthorized)
{
NSLog(@"%@", @"You have camera access");
}
else if(authStatus == AVAuthorizationStatusDenied)
{
NSLog(@"%@", @"Denied camera access");
[AVCaptureDevice requestAccessForMediaType:AVMediaTypeVideo completionHandler:^(BOOL granted) {
if(granted){
NSLog(@"Granted access to %@", AVMediaTypeVideo);
} else {
[self.presentedViewController dismissViewControllerAnimated:YES completion:nil];
UIAlertController* alert = [UIAlertController alertControllerWithTitle:@“no camera access“
message: @“if you need to use camera in this application go to settings -> appName -> and turn on camera.”
preferredStyle:UIAlertControllerStyleAlert];
UIAlertAction* defaultAction = [UIAlertAction actionWithTitle:@“ok” style:UIAlertActionStyleDefault
handler:^(UIAlertAction * action) {
}];
[alert addAction:defaultAction];
[self presentViewController:alert animated:YES completion:nil];
NSLog(@"Not granted access to %@", AVMediaTypeVideo);
return ;
}
}];
}
else if(authStatus == AVAuthorizationStatusRestricted)
{
[self.presentedViewController dismissViewControllerAnimated:YES completion:nil];
UIAlertController* alert = [UIAlertController alertControllerWithTitle:@“no camera access“
message: @“if you need to use camera in this application go to settings -> appName -> and turn on camera.”
preferredStyle:UIAlertControllerStyleAlert];
UIAlertAction* defaultAction = [UIAlertAction actionWithTitle:@“ok” style:UIAlertActionStyleDefault
handler:^(UIAlertAction * action) {
}];
[alert addAction:defaultAction];
[self presentViewController:alert animated:YES completion:nil];
NSLog(@"%@", @"Restricted, normally won't happen");
}
else if(authStatus == AVAuthorizationStatusNotDetermined)
{
NSLog(@"%@", @"Camera access not determined. Ask for permission.");
[AVCaptureDevice requestAccessForMediaType:AVMediaTypeVideo completionHandler:^(BOOL granted) {
if(granted){
NSLog(@"Granted access to %@", AVMediaTypeVideo);
} else {
NSLog(@"Not granted access to %@", AVMediaTypeVideo);
return ;
}
}];
}
else
{
[self.presentedViewController dismissViewControllerAnimated:YES completion:nil];
UIAlertController* alert = [UIAlertController alertControllerWithTitle:@“No camera access“
message: @“error accusing camera”
preferredStyle:UIAlertControllerStyleAlert];
UIAlertAction* defaultAction = [UIAlertAction actionWithTitle:@“ok” style:UIAlertActionStyleDefault
handler:^(UIAlertAction * action) {
}];
[alert addAction:defaultAction];
[self presentViewController:alert animated:YES completion:nil];
return;
//NSLog(@"%@", @"Camera access unknown error.");
}
if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {
UIImagePickerController *pickerView =[[UIImagePickerController alloc]init];
pickerView.allowsEditing = YES;
pickerView.delegate = self;
pickerView.sourceType = UIImagePickerControllerSourceTypeCamera;
if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPad) {
[ self.presentedViewController dismissViewControllerAnimated:YES completion:nil ];
pickerView.modalPresentationStyle = UIModalPresentationPopover;
UIPopoverPresentationController *popPC = pickerView.popoverPresentationController;
popPC.sourceView = attachButton;
popPC.permittedArrowDirections = UIPopoverArrowDirectionAny;
[self presentViewController:pickerView animated:YES completion:nil];
} else {
[self presentModalViewController:pickerView animated:YES ];
}
}
}else if( buttonIndex == 0 ) {
ALAuthorizationStatus status = [ALAssetsLibrary authorizationStatus];
switch (status) {
case ALAuthorizationStatusRestricted:
case ALAuthorizationStatusDenied:
{
[self.presentedViewController dismissViewControllerAnimated:YES completion:nil];
UIAlertController* alert = [UIAlertController alertControllerWithTitle:@“no access to library”
message: @“if you wish to access photos in this app go to settings -> appName-> and turn on photos .”
preferredStyle:UIAlertControllerStyleAlert];
UIAlertAction* defaultAction = [UIAlertAction actionWithTitle:@“ok” style:UIAlertActionStyleDefault
handler:^(UIAlertAction * action) {
}];
[alert addAction:defaultAction];
[self presentViewController:alert animated:YES completion:nil];
}
break;
default:
{
UIImagePickerController *pickerView = [[UIImagePickerController alloc] init];
pickerView.allowsEditing = YES;
pickerView.delegate = self;
[pickerView setSourceType:UIImagePickerControllerSourceTypePhotoLibrary];
if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPad) {
[ self.presentedViewController dismissViewControllerAnimated:YES completion:nil ];
pickerView.modalPresentationStyle = UIModalPresentationPopover;
UIPopoverPresentationController *popup = pickerView.popoverPresentationController;
popup.sourceView = attachButton;
popup.permittedArrowDirections = UIPopoverArrowDirectionAny;
[self presentViewController:pickerView animated:YES completion:nil];
} else {
[self presentModalViewController:pickerView animated:YES ];
}
}
break;
}
}
}
#pragma mark - PickerDelegates
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info{
[self dismissModalViewControllerAnimated:true];
UIImage * img = [info valueForKey:UIImagePickerControllerEditedImage];
image = img;
}