SubviewAttachingTextView

SubviewAttachingTextView is a UITextView subclass that allows embedding subviews in its attributed text as text attachments. The library also provides a SubviewAttachingTextViewBehavior class that allows compositing the attachment behavior in existing UITextView subclasses.

To see SubviewAttachingTextView in action, clone or download this repository and check out Example.playground inside SubviewAttachingTextView.xcworkspace.

How it works

SubviewAttachingTextView is built on top of NSTextAttachment and Text Kit APIs available through UITextView. A custom subclass of NSTextAttachment allows keeping a reference to the embedded views, and text view's NSLayoutManager and NSTextContainer allow querying for the attachments' bounds as they're laid out inside the text, taking into account all paragraph style properties. NSLayoutManager's and NSTextStorage's delegate callbacks allow implementing automatic layout and attachment updates.

Requirements

Xcode 11.0+ (written in Swift 5.0).
- For compatibility with Swift 4.2, use version 1.4.0.
- For compatibility with Swift 4.0, use version 1.3.0.
- For compatibility with Swift 3.x, use version 1.2.2.
iOS 8.0+
Compatible with Objective-C.

Installation

Carthage

Add the following line to your Cartfile:

github "vlas-voloshin/SubviewAttachingTextView"

Follow the instructions outlined in Carthage documentation to build and integrate the library into your app.

CocoaPods

Add the following line to your Podfile:
```
pod 'SubviewAttachingTextView'
```
Execute pod install.

Manual

Download and copy the repository source files into your project, or add it as a submodule to your git repository.
Drag&drop SubviewAttachingTextView.xcodeproj into your project or workspace in Xcode.
In "General" tab of Project Settings → Your Target, you might find that Xcode has added a missing framework item in "Embedded Binaries". Delete it for now.
Still in "General" tab, add SubviewAttachingTextView.framework to "Embedded Binaries". This should also add it to "Linked Frameworks and Libraries".

Usage

There are two ways to integrate the subview attachment behavior in your text views; choose the one that fits your needs:

As a drop-in `UITextView` replacement

Simply change the class of UITextView you use to SubviewAttachingTextView (in Swift code) or VVSubviewAttachingTextView (in Objective-C code and Interface Builder).

In custom subclasses

You can easily integrate SubviewAttachingTextViewBehavior class into your custom UITextView subclass by following the implementation of SubviewAttachingTextView:

In both init(frame:, textContainer:) and init?(coder:) initializers, create a SubviewAttachingTextViewBehavior object (VVSubviewAttachingTextViewBehavior in Objective-C), store it in your text view instance.
Assign your text view to the behavior's textView property. It's a weak property, so this won't create a retain cycle.
Assing the behavior object to the text view's layoutManager.delegate and textStorage.delegate. This will enable the automatic attachment management.
- If your custom text view already needs a different object to be its layout manager's or text storage's delegate, you can manually proxy the calls to layoutManager(_:, didCompleteLayoutFor:, atEnd:) and textStorage(_:, didProcessEditing:, range:, changeInLength:) delegate methods, but keep in mind that SubviewAttachingTextViewBehavior might require more methods in future.
Override the setter of textContainerInset property of your text view and make it call layoutAttachedSubviews() method of the attachment behavior. This ensures that the layout of attachments is updated when container insets are changed.

Attaching subviews

To embed a view in your text, do the following:

Create a SubviewTextAttachment instance (VVSubviewTextAttachment in Objective-C) and initialize it with a view object, optionally providing a size for the attachment.
- If you don't provide a size explicitly, the attachment will attempt to use the view's fitting size (calculated using Auto Layout), falling back to the view's current size if a non-zero fitting size cannot be calculated.
Alternatively, initialize the attachment with a view provider: an object conforming to TextAttachedViewProvider protocol (VVTextAttachedViewProvider in Objective-C). Using a view provider allows rendering the attributed string with an attachment in multiple text views at the same time, with each text view receiving its own instance of a view representing the attachment from the view provider. TextAttachedViewProvider also allows customizing the attached view's size during text layout.
Create an NSAttributedString from the attachment using its init(attachment:) initializer.
Insert the resulting string into your attributed text and assign it on the text view (either SubviewAttachingTextView or your custom text view embedding a SubviewAttachingTextViewBehavior).
Adding and removing the attached subviews is managed automatically. If you want to remove an embedded subview, just remove the corresponding attachment from the text view's attributed text.
If your text view is editable, user will also be able to delete the attachment just like any other text.

Limitations

Using pasteboard operations (copy, cut, paste) with subview attachments in editable text views is not supported at the moment.
Text layout is not automatically updated if the attached view's intrinsic size changes. At the moment, to change the size of an attached subview, the layout manager needs to be notified to invalidate layout and display for the corresponding character range, or the attachment needs to be removed from the text attributes and then added back.

License

This library is available under the MIT license. See the LICENSE file for more info.

vlas-voloshin/SubviewAttachingTextView