问题
I have a UIImage
that contains multiple image frames and a duration which was sliced together from an animated GIF file. If I load the image in a UIWebView
it will animate as expected, but I want to use a UITextView
instead. The obvious choice is to use TextKit with a custom NSLayoutManger
and many custom NSAttributedString
attributes to achieve various drawing effects. I have a single UITextView
that I'd like to give a NSAttributedString
that contains NSTextAttachment
s for all of the images I need to display inline. It's working fine except for when I load one of these animated UIImages
, they do not animate through their frames. Any thoughts on how to accomplish this? I've come up with a theoretical option:
- For each animated image add a custom defined attribute
- When layout manager goes to draw backgrounds, iterate this attribute to locate the positions of the attachment.
- Callback to the text view to create
UIImageView
s with the animated image, add as a subview, and callstartAnimating
I have yet to try this, but it's fairly hacky. I'm wondering if there's a better option.
In summary: I want to animate a UIImage
inside a UITextView
via NSTextAttachment
inside a NSAttributedString
without the necessity for extra UIImageView
objects. You can ignore the fact that this was previously done with a UIWebView
. UIImage
has properties (images
, duration
) for setting up animated frames, which I currently have configured. If I assign it to a UIImageView
it animates, if I set it as a NSTextAttachment
, no animation.
I would appreciate any feedback. Thanks!
回答1:
I think this behaviour is because the UITextView
doesn't display the attachments using UIImageView
subviews. When I observe the view hierarchy with and without the NSTextAttachment
s added to the UITextView
, I don't see any new views (you can observe the view hierarchy using View Debugging in Xcode, or by saying [[[UIApplication sharedApplication] keyWindow] recursiveDescription]
). Presumably, the UITextView
just draws it's attachments directly.
That said, one way I can think of to include an animatable attachment is to create an animated UIImageView
yourself as a subview of the UITextView
, place it exactly where the NSLayoutManager
places the NSTextAttachment
, and scroll it whenever the UITextView scrolls. You can get the rectangle of the NSTextAttachment
from the NSLayoutManager
by calling boundingRectForGlyphRange:inTextContainer:
(possibly in layoutManager:didCompleteLayoutForTextContainer:atEnd:
).
来源:https://stackoverflow.com/questions/29949348/animated-uiimage-in-uitextview-with-textkit