boundingRectWithSize for NSAttributedString returning wrong size

Question

I am trying to get the rect for an attributed string  but the boundingRectWithSize call is not respecting the size I pass in and is returning a rect with a single line height as opposed to a large height  it is a long string   I have experimented by passing in a very large value for the height and also 0 as in the code below  but the rect returned is always the same   CGRect paragraphRect    attributedText boundingRectWithSize CGSizeMake 300 0 0    options NSStringDrawingUsesDeviceMetrics   context nil     Is this broken  or do I need to do something else to have it returned a rect for wrapped text

User · Answer

My final decision after long investigation:
- boundingRectWithSize function returns correct size for uninterrupted sequence of characters only! In case string contains spaces or something else (called by Apple "Some of the glyphs" ) - it is impossible to get actual size of rect needed to display text!
I have replaced spaces in my strings by letters and immediately got correct result.

Apple says here: https://developer.apple.com/documentation/foundation/nsstring/1524729-boundingrectwithsize

"This method returns the actual bounds of the glyphs in the string. Some of the glyphs (spaces, for example) are allowed to overlap the layout constraints specified by the size passed in, so in some cases the width value of the size component of the returned CGRect can exceed the width value of the size parameter."

So it is necessary to find some another way to calculate actual rect...

After long investigation process solution finally found!!! I am not sure it will work good for all cases related to UITextView, but main and important thing was detected!

boundingRectWithSize function as well as CTFramesetterSuggestFrameSizeWithConstraints (and many other methods) will calculate size and text portion correct when correct rectangle used. For example - UITextView has textView.bounds.size.width - and this value not actual rectangle used by system when text drawing on UITextView.

I found very interesting parameter and performed simple calculation in code:

CGFloat padding = textView.textContainer.lineFragmentPadding;  
CGFloat  actualPageWidth = textView.bounds.size.width - padding * 2;

And magic works - all my texts calculated correct now! Enjoy!

User · Answer

Encountered exactly same issue  To me  the issue is solved by TTTAttributedLabel s    CGSize sizeThatFitsAttributedString  NSAttributedString   attributedString                        withConstraints  CGSize size                 limitedToNumberOfLines  NSUInteger numberOfLines  method  as it provide accurate result

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textView textContainerInset   UIEdgeInsetsZero  NSString  string     Some string   NSDictionary  attributes     NSFontAttributeName  UIFont systemFontOfSize 12 0f   NSForegroundColorAttributeName  UIColor blackColor    NSAttributedString  attributedString     NSAttributedString alloc  initWithString string attributes attributes    textView setAttributedText attributedString   CGRect textViewFrame    textView attributedText boundingRectWithSize CGSizeMake CGRectGetWidth self view frame -8 0f  9999 0f  options  NSStringDrawingUsesLineFragmentOrigin NSStringDrawingUsesFontLeading  context nil   NSLog    f   ceilf textViewFrame size height      Works on all fonts perfectly

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Add Following methods in ur code for getting correct size of attribute string  1      -  CGFloat findHeightForText  NSAttributedString   text havingWidth  CGFloat widthValue andFont  UIFont   font        UITextView  textView     UITextView alloc  init        textView setAttributedText text        textView setFont font       CGSize size    textView sizeThatFits CGSizeMake widthValue  FLT MAX        return size height       2  Call on heightForRowAtIndexPath method      int h    self findHeightForText attrString havingWidth yourScreenWidth andFont urFont

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I had the same problem  but I recognised that height constrained has been set correctly  So I did the following   - CGSize MaxHeighForTextInRow  NSString   RowText width  float UITextviewWidth        CGSize constrainedSize   CGSizeMake UITextviewWidth  CGFLOAT MAX        NSDictionary  attributesDictionary    NSDictionary dictionaryWithObjectsAndKeys                                             UIFont fontWithName   HelveticaNeue  size 11 0   NSFontAttributeName                                            nil        NSMutableAttributedString  string     NSMutableAttributedString alloc  initWithString RowText attributes attributesDictionary        CGRect requiredHeight    string boundingRectWithSize constrainedSize options NSStringDrawingUsesLineFragmentOrigin context nil        if  requiredHeight size width  gt  UITextviewWidth            requiredHeight   CGRectMake 0  0  UITextviewWidth  requiredHeight size height              return requiredHeight size

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Ed McManus has certainly provided a key to getting this to work  I found a case that does not work  UIFont  font       UIColor  color       NSDictionary  attributesDictionary    NSDictionary dictionaryWithObjectsAndKeys                                       font  NSFontAttributeName                                       color  NSForegroundColorAttributeName                                       nil    NSMutableAttributedString  string     NSMutableAttributedString alloc  initWithString  someString attributes attributesDictionary     string appendAttributedString    NSAttributedString alloc  initWithString  anotherString    CGRect rect    string boundingRectWithSize constraint options  NSStringDrawingUsesLineFragmentOrigin NSStringDrawingUsesFontLeading  context nil     rect will not have the correct height  Notice that anotherString  which is appended to string  was initialized without an attribute dictionary  This is a legitimate initializer for anotherString but boundingRectWithSize  does not give an accurate size in this case

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warrenm Sorry to say that framesetter method didn t work for me   I got this This function can help us to determine the frame size needed for a string range of an NSAttributedString in iphone Ipad SDK for a given Width    It can be used for a dynamic height of UITableView Cells  -  CGSize frameSizeForAttributedString  NSAttributedString   attributedString       CTTypesetterRef typesetter   CTTypesetterCreateWithAttributedString  CFAttributedStringRef attributedString       CGFloat width   YOUR FIXED WIDTH       CFIndex offset   0  length      CGFloat y   0      do           length   CTTypesetterSuggestLineBreak typesetter  offset  width           CTLineRef line   CTTypesetterCreateLine typesetter  CFRangeMake offset  length             CGFloat ascent  descent  leading          CTLineGetTypographicBounds line   amp ascent   amp descent   amp leading            CFRelease line            offset    length          y    ascent   descent   leading        while  offset  lt   attributedString length         CFRelease typesetter        return CGSizeMake width  ceil y        Thanks to HADDAD ISSA     http   haddadissa blogspot in 2010 09 compute-needed-heigh-for-fixed-width-of html

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I ve found that the preferred solution does not handle line breaks   I ve found this approach works in all cases   UILabel  dummyLabel    UILabel new    dummyLabel setFrame CGRectMake 0  0  desiredWidth  CGFLOAT MAX    dummyLabel numberOfLines   0   dummyLabel setLineBreakMode NSLineBreakByWordWrapping   dummyLabel attributedText   myString   dummyLabel sizeToFit   CGSize requiredSize   dummyLabel frame size

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Turns out that EVERY part of an NSAttributedString must have a dictionary set with at least NSFontAttributeName and NSForegroundColorAttributeName set  if you wish boundingRectWithSize to actually work    I don t see that documented anywhere

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In case you d like to get bounding box by truncating the tail  this question can help you out   CGFloat maxTitleWidth   200   NSMutableParagraphStyle  paragraph     NSMutableParagraphStyle alloc  init   paragraph lineBreakMode   NSLineBreakByTruncatingTail   NSDictionary  attributes     NSFontAttributeName   self textLabel font                               NSParagraphStyleAttributeName  paragraph    CGRect box    self textLabel text               boundingRectWithSize CGSizeMake maxTitleWidth  CGFLOAT MAX                options  NSStringDrawingUsesLineFragmentOrigin   NSStringDrawingUsesFontLeading                attributes attributes context nil

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For some reason  boundingRectWithSize always returns wrong size  I figured out a solution  There is a method for UItextView -sizeThatFits which returns the proper size for the text set  So instead of using boundingRectWithSize  create an UITextView  with a random frame  and call its sizeThatFits with the respective width and CGFLOAT MAX height  It returns the size that will have the proper height      UITextView  view   UITextView alloc  initWithFrame CGRectMake 0  0  width  10          view text text     CGSize size  view sizeThatFits CGSizeMake width  CGFLOAT MAX       height size height     If you are calculating the size in a while loop  do no forget to add that in an autorelease pool  as there will be n number of UITextView created  the run time memory of the app will increase if we do not use autoreleasepool

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NSDictionary  stringAttributes    NSDictionary dictionaryWithObjectsAndKeys                                         UIFont systemFontOfSize 18   NSFontAttributeName                                         UIColor blackColor   NSForegroundColorAttributeName                                        nil        NSAttributedString  attributedString     NSAttributedString alloc  initWithString myLabel text attributes stringAttributes       myLabel attributedText   attributedString    this is the key       CGSize maximumLabelSize   CGSizeMake  screenRect size width - 40  CGFLOAT MAX        CGRect newRect    myLabel text boundingRectWithSize maximumLabelSize                                                        options  NSStringDrawingUsesLineFragmentOrigin NSStringDrawingUsesFontLeading                                                      attributes stringAttributes context nil        self myLabelHeightConstraint constant   ceilf newRect size height     I tried everything on this page and still had one case for a UILabel that was not formatting correctly   Actually setting the attributedText on the label finally fixed the problem

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Swift four version  let string    A great test string   let font   UIFont systemFont ofSize  14  let attributes   NSAttributedStringKey  Any      font  font  let attributedString   NSAttributedString string  string  attributes  attributes  let largestSize   CGSize width  bounds width  height   greatestFiniteMagnitude     Option one  best option  let framesetter   CTFramesetterCreateWithAttributedString attributedString  let textSize   CTFramesetterSuggestFrameSizeWithConstraints framesetter  CFRange    nil  largestSize  nil     Option two let textSize    string as NSString  boundingRect with  largestSize  options    usesLineFragmentOrigin    usesFontLeading   attributes  attributes  context  nil  size    Option three let textSize   attributedString boundingRect with  largestSize  options    usesLineFragmentOrigin    usesFontLeading   context  nil  size   Measuring the text with the CTFramesetter works best as it provides integer sizes and handles emoji s and other unicode characters well

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NSAttributedString  attributedText     NSAttributedString alloc                                            initWithString joyMeComment content                                           attributes    NSFontAttributeName   UIFont systemFontOfSize TextFont    autorelease        CGRect paragraphRect        attributedText boundingRectWithSize CGSizeMake kWith  CGFLOAT MAX                                   options  NSStringDrawingUsesLineFragmentOrigin NSStringDrawingUsesFontLeading                                   context nil       contentSize   paragraphRect size       contentSize size height  10      label frame contentSize    if label s frame not add 10 this method will never work  hope this can help you  goog luck

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I d like to add my thoughts since I had exactly the same problem   I was using UITextView since it had nicer text alignment  justify  which at the time was not available in UILabel   but in order to  simulate  non-interactive-non-scrollable UILabel  I d switch off completely scrolling  bouncing  and user interaction   Of course  problem was that text was dynamic  and while width would be fixed  height should be recalculated every time I d set new text value   boundingRectWithSize didn t work well for me at all  from what I could see  UITextView was adding some margin on top which boundingRectWithSize would not get into a count  hence  height retrieved from boundingRectWithSize was smaller than it should be   Since text was not to be updated rapidly  it s just used for some information that may update every 2-3 seconds the most  I ve decided following approach      This f is nested in a custom UIView-inherited class that is built using xib file    - void  setTextAndAutoSize  NSString  text inTextView  UITextView  tv       CGFloat msgWidth   tv frame size width     get target s width         Make  test  UITextView to calculate correct size     UITextView  temp     UITextView alloc  initWithFrame CGRectMake 0  0  msgWidth  300       we set some height  really doesn t matter  just put some value like this one         Set all font and text related parameters to be exact as the ones in targeted text view      temp setFont tv font        temp setTextAlignment tv textAlignment        temp setTextColor tv textColor        temp setText text           Ask for size that fits  P     CGSize tv size    temp sizeThatFits CGSizeMake msgWidth  300            kill this  test  UITextView  it s purpose is over      temp release       temp   nil          apply calculated size  if calcualted width differs  I choose to ignore it anyway and use only height because I want to have width absolutely fixed to designed value     tv frame   CGRectMake tv frame origin x  tv frame origin y  msgWidth  tv size height         Above code is not directly copied from my source  I had to adjust it   clear it from bunch of other stuff not needed for this article  Don t take it for copy-paste-and-it-will-work-code   Obvious disadvantage is that it has alloc and release  for each call    But  advantage is that you avoid depending on compatibility between how boundingRectWithSize draws text and calculates it s size and implementation of text drawing in UITextView  or UILabel which also you can use just replace UITextView with UILabel   Any  bugs  that Apple may have are this way avoided   P S  It would seem that you shouldn t need this  temp  UITextView and can just ask sizeThatFits directly from target  however that didn t work for me  Though logic would say it should work and alloc release of temporary UITextView are not needed  it did not  But this solution worked flawlessly for any text I would set in

User · Answer

I have had the same problem with not getting an accurate size using these techniques and I ve changed my approach to make it work    I have a long attributed string which I ve been trying to fit into a scroll view so that it shows properly without being truncated  What I did to make the text work reliably was to not set the height at all as a constraint and instead allowed the intrinsic size to take over  Now the text is displayed correctly without being truncated and I do not have to calculate the height   I suppose if I did need to get the height reliably I would create a view which is hidden and these constraints and get the height of the frame once the constraints are applied

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Many of the answers here are great  David Rees summarises the options nicely  But sometimes when there are special characters or multiple white spaces the size seemed to always be wrong  Example of a not working string  for me    quot hello           world quot   What I found out is that setting the kern of the NSAttributedString to 1 helps returning the right size  Like this  NSAttributedString      string   quot some string quot       attributes             font  NSFont preferredFont forTextStyle   body             kern  1

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I didn t have luck with any of these suggestions  My string contained unicode bullet points and I suspect they were causing grief in the calculation  I noticed UITextView was handling the drawing fine  so I looked to that to leverage its calculation  I did the following  which is probably not as optimal as the NSString drawing methods  but at least it s accurate  It s also slightly more optimal than initialising a UITextView just to call -sizeThatFits    NSTextContainer  textContainer     NSTextContainer alloc  initWithSize CGSizeMake width  CGFLOAT MAX    NSLayoutManager  layoutManager     NSLayoutManager alloc  init    layoutManager addTextContainer textContainer    NSTextStorage  textStorage     NSTextStorage alloc  initWithAttributedString formattedString    textStorage addLayoutManager layoutManager    const CGFloat formattedStringHeight   ceilf  layoutManager usedRectForTextContainer textContainer  size height

User · Answer

Looks like you weren t providing the correct options  For wrapping labels  provide at least   CGRect paragraphRect      attributedText boundingRectWithSize CGSizeMake 300 f  CGFLOAT MAX    options  NSStringDrawingUsesLineFragmentOrigin NSStringDrawingUsesFontLeading    context nil     Note  if the original text width is under 300 f there won t be line wrapping  so make sure the bound size is correct  otherwise you will still get wrong results

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One thing I was noticing is that the rect that would come back from  CGRect boundingRectWithSize  CGSize size options  NSStringDrawingOptions options attributes  NSDictionary   attributes context  NSStringDrawingContext   context would have a larger width than what I passed in   When this happened my string would be truncated   I resolved it like this   NSString  aLongString       NSInteger width     some width              UIFont  font     your font  CGRect rect    aLongString boundingRectWithSize CGSizeMake width  CGFLOAT MAX                                          options  NSStringDrawingUsesFontLeading   NSStringDrawingUsesLineFragmentOrigin                                       attributes    NSFontAttributeName   font                                                     NSForegroundColorAttributeName    UIColor whiteColor                                           context nil    if rect size width  gt  width        return rect size height   font lineHeight    return rect size height    For some more context  I had multi line text and I was trying to find the right height to display it in  boundRectWithSize was sometimes returning a width larger than what I would specify  thus when I used my past in width and the calculated height to display my text  it would truncate  From testing when boundingRectWithSize used the wrong width the amount it would make the height short by was 1 line  So I would check if the width was greater and if so add the font s lineHeight to provide enough space to avoid truncation

User · Answer

Im a little late to the game - but I have been trying to figure out a way that works to find the bounding box that will fit around an attributed string to make a focus ring like editing a file in Finder does  everything I had tried failed when there are spaces at the end of the string or multiple spaces inside the string  boundingRectWithSize fails miserably for this as well as CTFramesetterCreateWithAttributedString    Using a NSLayoutManager the following code seems to do the trick in all the cases I have found so far and returns a rect that perfectly bounds the string  Bonus  if you select the text the edges of the selection go right up to the bounds of the rect returned  The code below uses the layoutManager from a NSTextView   NSLayoutManager  layout    self layoutManager   NSTextContainer  container    self textContainer    CGRect focusRingFrame    layout boundingRectForGlyphRange NSMakeRange 0    self textStorage  length   inTextContainer container

User · Answer

Ok so I spent lots of time debugging this  I found out that the maximum text height as defined by boundingRectWithSize allowed to display text by my UITextView was lower than the frame size   In my case the frame is at most 140pt but the UITextView tolerate texts at most 131pt   I had to figure that out manually and hardcode the  real  maximum height   Here is my solution   -  BOOL textView  UITextView   textView shouldChangeTextInRange  NSRange range replacementText  NSString   text       NSString  proposedText    textView text stringByReplacingCharactersInRange range withString text       NSMutableAttributedString  attributedText     NSMutableAttributedString alloc  initWithString proposedText       CGRect boundingRect      CGFloat maxFontSize   100      CGFloat minFontSize   30      CGFloat fontSize   maxFontSize   1      BOOL fit      NSLog   Trying text           proposedText       do           fontSize -  1            XXX Seems like trailing whitespaces count for 0  find a workaround          attributedText addAttribute NSFontAttributeName value  textView font fontWithSize fontSize  range NSMakeRange 0  attributedText length            CGFloat padding   textView textContainer lineFragmentPadding          CGSize boundingSize   CGSizeMake textView frame size width - padding   2  CGFLOAT MAX           boundingRect    attributedText boundingRectWithSize boundingSize options NSStringDrawingUsesLineFragmentOrigin NSStringDrawingUsesFontLeading context nil           NSLog   bounding rect for font  f is      max is  f  f   Padding   f   fontSize  NSStringFromCGRect boundingRect   textView frame size width  148 0  padding           fit    boundingRect size height  lt   131        while   fit  amp  amp  fontSize  gt  minFontSize       if  fit            self textView font    self textView font fontWithSize fontSize           NSLog   Fit           else           NSLog   No fit              return fit

[objective-c] boundingRectWithSize for NSAttributedString returning wrong size

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