iOS 7.0 UITextView gettings terribly slow after adding images to it

Question

I am trying to make a text editor using UITextView in ios7 and above, but I am facing some terrible bugs. I have gone through many Stack Overflow questions related to scrolling of textview. But the main issue about which I am not able to find is slow rendering of text after adding NSTextAttachment(Custom) to it. I am using the approach described on this post:

http://ossh.com.au/design-and-technology/software-development/implementing-rich-text-with-images-on-os-x-and-ios/

But after adding the images the typing of text becomes terribly slow. The code is almost the same as described in the post so I have not pasted it here. The reason can be as said in the following question: ios - iOS 7 UITextView is slow after typing lots of text

"drawGlyphsForGlyphRange runs N*2 times, where N is the number of times your lines word-wrapped."

But I am not sure. Any advice in a direction to solve this terribly slow rendering of text?

nick28 nick28 · Accepted Answer · 2014-04-25T17:46:32

I have solved the lag by scaling the images when adding using the following code

-(void)insertImage:(UIImage *)image
{
NSTextAttachment* attachment = [[NSTextAttachment alloc] initWithData:UIImageJPEGRepresentation(image, 0.0) ofType:@"image/jpeg"];

    float scalingFactor = 1.0;

    CGSize imageSize = [image size];
    float width = self.frame.size.width;
    if (width < imageSize.width)
        scalingFactor = (width)*scalingFactor / imageSize.width;

    CGRect rect = CGRectMake(0, 0, imageSize.width*scalingFactor, imageSize.height *scalingFactor);
    attachment.image = [self imageWithImage:image scaledToSize:rect.size];
    attachment.bounds = [self scaleImageSizeToWidth:self.frame.size.width withImage:image];
    NSRange range = [self selectedRange];
    NSAttributedString* attachmentchar =
    [NSAttributedString attributedStringWithAttachment:attachment];
    [[self textStorage] insertAttributedString:attachmentchar atIndex:range.location];

}

I noticed using the - (void)textStorage:(NSTextStorage *)textStorage willProcessEditing:(NSTextStorageEditActions)editedMask range:(NSRange)editedRange changeInLength:(NSInteger)delta and enumerating the text storage for attachments and replacing them with custom nstextattachment subclass is not productive and is slowing down the rendering a lot.

iOS 7.0 UITextView gettings terribly slow after adding images to it

1 Answers