{"id":350,"date":"2016-07-08T11:27:52","date_gmt":"2016-07-08T09:27:52","guid":{"rendered":"https:\/\/zaven.co\/blog\/?p=350"},"modified":"2025-04-08T19:55:20","modified_gmt":"2025-04-08T17:55:20","slug":"add-extensions-ios-apps","status":"publish","type":"post","link":"https:\/\/zaven.co\/blog\/add-extensions-ios-apps\/","title":{"rendered":"How to add extensions to iOS apps (part 4)"},"content":{"rendered":"

Welcome to the last part of our tutorial: how to add extensions to iOS apps<\/a>. In this part, we will learn how to add data using a service from our extension<\/strong>.<\/p>\n

In part three of \u201cHow to add extensions to iOS apps\u201d we finished table implementation in the main app<\/a>.<\/p>\n

Adding files<\/h2>\n

Start by opening the ActionViewController<\/code> of our extension. We can see quite a lot of code here.<\/p>\n

By default, it is used for handling photos which are opened through the extension<\/strong>. We\u2019re going to modify this template (or rather \u201crewrite it\u201d). The first step is to delete the function logic in viewDidLoad()<\/code>.<\/p>\n

\nimport UIKit\nimport MobileCoreServices\n\nclass ActionViewController: UIViewController {\n\n    override func viewDidLoad() {\n        super.viewDidLoad()\n    }\n    \n    override func didReceiveMemoryWarning() {\n        super.didReceiveMemoryWarning()\n    }\n\t\n\t@IBAction func done() {\n\t\tself.extensionContext!.completeRequestReturningItems(self.extensionContext!.inputItems, completionHandler: nil)\n\t}\n\n}\n<\/code><\/pre>\n
We\u2019ll get back to it in a minute, but let\u2019s have a look at the Info.plist<\/code> file in our extension. We must define what kind of files will it accept. Look for a setting called NSExtension<\/code>: there you can find a dictionary called NSExtensionAttributes<\/code> with the NSExtensionActivationRule<\/code> key. Determine the file types there.<\/p>\n
\"how<\/a>
Defining file types<\/p><\/div>\n
If you\u2019d like to find out more, you can find the docs for this topic<\/a> here. Apple provides a few elementary file types which we can use. Unfortunately, there are only a couple of them. And sometimes it turns out that they are too common for an app\u2019s specific requirements. In that case, it is useful to find out what the UTI<\/a> is. We will use a table<\/a> in which all required file types stored.<\/p>\n
Assume that I want the extension to accept only.pdf<\/em>, .txt <\/em>and .doc<\/em> extensions. We need more than basic settings to determine these types of files<\/em>. To make it easier, we can use Predicate Format String<\/code>. Right-click the fileInfo.plist <\/code>and select Open As\/Source Code<\/code>.<\/p>\n
Now we can see the content of an XML format file<\/strong>. Look for a key called NSExtensionActivationRule<\/code> and delete the string TRUEPREDICATE<\/code>. By default, this string enables all file types (but this also guarantees our app to be rejected from the App Store).<\/p>\n
Instead of this string, paste following one:<\/p>\n
\n<key>NSExtensionActivationRule<\/key>\n<string>SUBQUERY (\n  extensionItems,\n  $extensionItem,\n  SUBQUERY (\n    $extensionItem.attachments,\n    $attachment,\n    ANY $attachment.registeredTypeIdentifiers UTI-CONFORMS-TO \"com.adobe.pdf\" ||\n    ANY $attachment.registeredTypeIdentifiers UTI-CONFORMS-TO \"public.plain-text\" ||\n    ANY $attachment.registeredTypeIdentifiers UTI-CONFORMS-TO \"com.microsoft.word.doc\"\n  ).@count == $extensionItem.attachments.@count\n).@count == 1<\/string>\n<\/code><\/pre>\n
It allows us to use the following types of files:<\/p>\n