[objective-c] boundingRectWithSize for NSAttributedString returning wrong size

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?

This question is related to objective-c nsattributedstring

The answer is


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!


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];

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 <= 131;
    } while (!fit && fontSize > minFontSize);
    if (fit) {
        self.textView.font = [self.textView.font fontWithSize:fontSize];
        NSLog(@"Fit!");
    } else {
        NSLog(@"No fit");
    }
    return fit;
}

    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.


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.


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 > UITextviewWidth) {
        requiredHeight = CGRectMake(0, 0, UITextviewWidth, requiredHeight.size.height);
    }

    return requiredHeight.size;
}

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.


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):

"hello    .   .  world"

What I found out is that setting the kern of the NSAttributedString to 1 helps returning the right size.

Like this:

NSAttributedString(
    string: "some string",
    attributes: [
        .font: NSFont.preferredFont(forTextStyle: .body), 
        .kern: 1])

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.


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);

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!


@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, &ascent, &descent, &leading);

        CFRelease(line);

        offset += length;
        y += ascent + descent + leading;
    } while (offset < [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


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.


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];

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.


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];

    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.


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;

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 > 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.


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.


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.