我正在开发适用于iPhone和iPad的iOS应用，我有一个问题。
这是附加到UIBarButton的代码。
- (IBAction)saveFile:(id)sender {
NSURL *theRessourcesURL = [[self.webView request] URL];
NSString *filename = [theRessourcesURL lastPathComponent];
NSString *docPath = [self documentsDirectoryPath];
NSString *pathToDownloadTo = [NSString stringWithFormat:@"%@/%@", docPath, filename];
NSData *tmp = [NSData dataWithContentsOfURL:theRessourcesURL];
// Save the loaded data if loaded successfully
if (tmp != nil) {
NSError *error = nil;
// Write the contents of our tmp object into a file
[tmp writeToFile:pathToDownloadTo options:NSDataWritingAtomic error:&error];
if (error != nil) {
// Display an UIAlertView that shows the users we don't saved the file
UIAlertView *filenameAlert = [[UIAlertView alloc] initWithTitle:NSLocalizedString(@"Report don't saved",nil) message:[self titleAlert:filename] delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];
[filenameAlert show];
}
} else {
// Display an UIAlertView that shows the users we don't saved the file
UIAlertView *filenameAlert = [[UIAlertView alloc] initWithTitle:NSLocalizedString(@"Report don't saved",nil) message:[self titleAlert:filename] delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];
[filenameAlert show];
}
// "Open it and options.." menu
self.menuController = [UIDocumentInteractionController interactionControllerWithURL:[NSURL fileURLWithPath:pathToDownloadTo]];
self.menuController.delegate = self;
[self.menuController presentOpenInMenuFromBarButtonItem:self.navigationItem.rightBarButtonItem animated:YES];
[self.menuController presentOptionsMenuFromBarButtonItem:self.navigationItem.rightBarButtonItem animated:YES];
}
这样构建没有问题，并且在iOS 7下运行，这段代码运行正常。
问题是，在iOS 8+中，当在iPad上运行时，它会显示此警告：
LaunchServices: invalidationHandler called
Warning: Attempt to present <_UIDocumentActivityViewController: 0x1601004c0> on <UINavigationController: 0x15cd9a650> while a presentation is in progress!
在界面上＆＃34;打开...＆＃34;菜单快速显示和隐藏，用户无法在菜单上选择任何选项。在iPhone上也出现警告，但是＆＃34;打开...＆＃34;菜单工作正常。