How to get NSParagraphStyleAttributeName from NSMutableAttributeString?

Question

I create an NSMutableAttributedString with alignment as follows:

UIFont * font =  [UIFont systemFontOfSize:[UIFont labelFontSize]];
/// Make a copy of the default paragraph style
NSMutableParagraphStyle *paragraphStyle = [[NSParagraphStyle defaultParagraphStyle] mutableCopy];
/// Set line break mode
paragraphStyle.lineBreakMode = NSLineBreakByWordWrapping;
/// Set text alignment
paragraphStyle.alignment = alignmentForString(textString) ;//NSTextAlignmentLeft;//NSTextAlignmentRight;// NSTextAlignmentNatural;//  NSTextAlignmentLeft;

NSDictionary *messageDrawRectAttributesDictionary = @{
                        NSFontAttributeName: font,
                        NSParagraphStyleAttributeName: paragraphStyle,
                        NSForegroundColorAttributeName:[UIColor blackColor]
                        };

NSMutableAttributedString * mutalbleAttributedString = [[NSMutableAttributedString alloc] initWithString:textString attributes:messageDrawRectAttributesDictionary];

I want to know (for later use in the app) how to get what alignment I set in this string.

I tried this code, without understanding exactly what I'm doing:

NSRange range = NSMakeRange(0,mutalbleAttributedString.length-1);
NSDictionary * paraDic =[mutalbleAttributedString attribute:NSParagraphStyleAttributeName atIndex:0 longestEffectiveRange:&range inRange:range];

Now, I search for a lot of sample code and I read the Apple docs. But no luck. I get empty dictionary.

The only help I need is if someone can just write the right code that will return me the data of the alignment.

score 4 · Accepted Answer · answered Oct 31 '15 at 16:11

When you call attribute:atIndex:longestEffectiveRange:inRange:, the return value is the value of the requested attribute, not a dictionary. Also, do not pass in range for both range parameters.

Your code should be something like this:

NSRange range = NSMakeRange(0, mutalbleAttributedString.length);
NSParagraphStyle *paraStyle = [mutalbleAttributedString attribute:NSParagraphStyleAttributeName atIndex:0 longestEffectiveRange:NULL inRange:range];
NSTextAlignment alignment = paraStyle.alignment;

Note the following changes:

The proper return value for the attribute being requested
Settings the proper length for range
Passing NULL for the longestEffectiveRange: since you don't care about that value.

great ! that's works ! thanks ! hope this help for others too!! — user1105951, Oct 31 '15 at 16:23

joern · Answer 2 · 2015-10-31T16:14:12.290

1

You can get the alignment from the NSMutableAttributedString like this:

 NSRange range = NSMakeRange(0, mutableAttributedString.length);
 NSDictionary *attributes = [mutableAttributedString attributesAtIndex:0 effectiveRange:&range];
 NSMutableParagraphStyle *paragraphStyle = attributes[NSParagraphStyleAttributeName];
 NSTextAlignment alignment = paragraphStyle.alignment;

edited Oct 31 '15 at 16:14

answered Oct 31 '15 at 16:11

joern

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1. `range` is incorrect. 2. Do not hardcode the key to get the attribute. Use the proper constant provided by the API. – rmaddy Oct 31 '15 at 16:12
Thanks for your comment! You are right, I edited my answer. – joern Oct 31 '15 at 16:14

score 0 · Answer 3 · answered Feb 02 '21 at 05:19

Swift 5 example:

var effectiveRange = NSMakeRange(0, attributedString.length)
let currentParagraphStyle: NSParagraphStyle = attributedText?.attribute(NSAttributedString.Key.paragraphStyle, at: 0, effectiveRange: &effectiveRange) as! NSParagraphStyle
let align = currentParagraphStyle.alignment
let lineSpacing = currentParagraphStyle.lineSpacing
let newParagraphStyle = currentParagraphStyle.lineHeightMultiple

How to get NSParagraphStyleAttributeName from NSMutableAttributeString?

3 Answers3