CGRect for selected UITextRange adjustment for multiline text?

问题

I've used this answer in order to create a CGRect for a certain range of text.

In this UITextView I've set it's attributedText (so I've got a bunch of styled text with varying glyph sizes).

This works great for the first line of text that's left aligned, but it has some really strange results when working with NSTextAlignmentJustified or NSTextAlignmentCenter.

It also doesn't calculate properly when the lines wrap around or (sometimes) if there are \n line breaks.

I get stuff like this (this is center aligned):

When instead I expect this:

This one has a \n line break - the first two code bits were highlighted successfully, but the last one more code for you to see was not because the text wrapping isn't factored into the x,y calculations.

Here's my implementation:

- (void)formatMarkdownCodeBlockWithAttributes:(NSDictionary *)attributesDict
                      withHighlightProperties:(NSDictionary *)highlightProperties
                               forFontSize:(CGFloat)pointSize
{
    NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"`.+?`" options:NO error:nil];
    NSArray *matchesArray = [regex matchesInString:[self.attributedString string] options:NO range:NSMakeRange(0, self.attributedString.length)];
    for (NSTextCheckingResult *match in matchesArray)
    {
        NSRange range = [match range];
        if (range.location != NSNotFound) {

            self.textView.attributedText = self.attributedString;

            CGRect codeRect = [self frameOfTextRange:range forString:[[self.attributedString string] substringWithRange:range] forFontSize:pointSize];
            UIView *highlightView = [[UIView alloc] initWithFrame:codeRect];
            highlightView.layer.cornerRadius = 4;
            highlightView.layer.borderWidth = 1;
            highlightView.backgroundColor = [highlightProperties valueForKey:@"backgroundColor"];
            highlightView.layer.borderColor = [[highlightProperties valueForKey:@"borderColor"] CGColor];
            [self.contentView insertSubview:highlightView atIndex:0];

            [self.attributedString addAttributes:attributesDict range:range];

            //strip first and last `
            [[self.attributedString mutableString] replaceOccurrencesOfString:@"(^`|`$)" withString:@" " options:NSRegularExpressionSearch range:range];
        }
    }
}

- (CGRect)frameOfTextRange:(NSRange)range forString:(NSString *)string forFontSize:(CGFloat)pointSize
{
    self.textView.selectedRange = range;
    UITextRange *textRange = [self.textView selectedTextRange];
    CGRect rect = [self.textView firstRectForRange:textRange];
    //These three lines are a workaround for getting the correct width of the string since I'm always using the monospaced Menlo font.
    rect.size.width = ((pointSize / 1.65) * string.length) - 4;
    rect.origin.x+=2;
    rect.origin.y+=2;
    return rect;
}

Oh, and in case you want it, here's the string I'm playing with:

*This* is **awesome** @mention `code` more \n `code and code` #hashtag [markdown](http://google.com) __and__ @mention2 {#FFFFFF|colored text} This**will also** work but ** will not ** **work** Also, some `more code for you to see`

Note: Please don't suggest I use TTTAttributedLabel or OHAttributedLabel.

回答1:

I think all your problems are because of incorrect order of instructions.

You have to

Set text aligment
Find required substrings and add specific attributes to them
And only then highlight strings with subviews.

Also you will not need to use "a workaround for getting the correct width of the string since I'm always using the monospaced Menlo font" in such a case.

I have simplified your code a little to make it more understandable.

Result:

- (void)viewDidLoad
{
    [super viewDidLoad];

    NSDictionary *basicAttributes = @{ NSFontAttributeName : [UIFont boldSystemFontOfSize:18],
                                       NSForegroundColorAttributeName : [UIColor blackColor] };
    NSDictionary *attributes = @{ NSFontAttributeName : [UIFont systemFontOfSize:15],
                                  NSForegroundColorAttributeName : [UIColor darkGrayColor]};


    _textView.attributedText = [[NSAttributedString alloc] initWithString:
                                @"*This* is **awesome** @mention `code` more \n `code and code` #hashtag [markdown](http://google.com) __and__ @mention2 {#FFFFFF|colored text} This**will also** work but ** will not ** **work** Also, some `more code for you to see`" attributes:attributes];
    _textView.textAlignment = NSTextAlignmentCenter;

    [self formatMarkdownCodeBlockWithAttributes:basicAttributes];
}

- (void)formatMarkdownCodeBlockWithAttributes:(NSDictionary *)attributesDict
{
    NSMutableString *theString = [_textView.attributedText.string mutableCopy];
    NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"`.+?`" options:NO error:nil];
    NSArray *matchesArray = [regex matchesInString:theString options:NO range:NSMakeRange(0, theString.length)];

    NSMutableAttributedString *theAttributedString = [_textView.attributedText mutableCopy];
    for (NSTextCheckingResult *match in matchesArray)
    {
        NSRange range = [match range];
        if (range.location != NSNotFound) {
            [theAttributedString addAttributes:attributesDict range:range];
        }
    }

    _textView.attributedText = theAttributedString;

    for (NSTextCheckingResult *match in matchesArray)
    {
        NSRange range = [match range];
        if (range.location != NSNotFound) {

            CGRect codeRect = [self frameOfTextRange:range];
            UIView *highlightView = [[UIView alloc] initWithFrame:codeRect];
            highlightView.layer.cornerRadius = 4;
            highlightView.layer.borderWidth = 1;
            highlightView.backgroundColor = [UIColor yellowColor];
            highlightView.layer.borderColor = [[UIColor redColor] CGColor];
            [_textView insertSubview:highlightView atIndex:0];
        }
    }
}

- (CGRect)frameOfTextRange:(NSRange)range
{
    self.textView.selectedRange = range;
    UITextRange *textRange = [self.textView selectedTextRange];
    CGRect rect = [self.textView firstRectForRange:textRange];
    return rect;
}

回答2:

I just had to do something similar to this. Assuming you are using iOS 7:

// Build the range that you want for your text
NSRange range = NSMakeRange(location, length);

// Get the substring of the attributed text at that range
NSAttributedString *substring = [textView.attributedText attributedSubstringFromRange:range];

// Find the frame that would enclose the substring of text.
CGRect frame = [substring boundingRectWithSize:maxSize
                                           options:(NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingUsesFontLeading)
                                           context:nil];

This should use the NSTextAlignment assigned to the attributed string.

回答3:

As @Avt answered https://stackoverflow.com/a/22572201/3549781 this question. I'm just answering for the newline problem. This newline problem occurs on iOS 7+ even if you use

[self.textView selectedTextRange] or [self.textView positionFromPosition: offset:]

We just have to ensure the layout of the textView before calling firstRectForRange by

[self.textView.layoutManager ensureLayoutForTextContainer:self.textView.textContainer];

Courtesy : https://stackoverflow.com/a/25983067/3549781

P.S : At first I added this as a comment to the question. As most people don't read comments I added this as an answer.

来源：https://stackoverflow.com/questions/22362131/cgrect-for-selected-uitextrange-adjustment-for-multiline-text

标签

ios

objective-c

uitextview

nsattributedstring