UIDocumentInteractionController

UIDocumentInteractionController  * documentInteraction = [UIDocumentInteractionController interactionControllerWithURL:[NSURL fileURLWithPath:kXmlFilePath]];
documentInteraction.delegate  = self;
// 支持文件类型，这里不说明就代表能打开所有文件的App！
documentInteraction.UTI = @"public.xml"; 
// 预览分享
[documentInteraction presentPreviewAnimated:YES];

#pragma mark - UIDocumentInteractionControllerDelegate
- (UIViewController *)documentInteractionControllerViewControllerForPreview:(UIDocumentInteractionController *)controller
{
    return self;
}
- (UIView *)documentInteractionControllerViewForPreview:(UIDocumentInteractionController *)controller
{
    return self.view;
}
- (CGRect)documentInteractionControllerRectForPreview:(UIDocumentInteractionController *)controller
{
    return self.view.frame;
}