Yossi Tsafar Yossi Tsafar - 2 months ago 41
iOS Question

Calculate the range of visible text in UILabel

I have an

UILabel
with fixed size, the text that I set into this
UILabel
can be 200, 5 or 500 characters long. What I want to do is to calculate how much visible text can I put into this
UILabel
with the current
UILabel
size.

Why I want to do that? Because I want to add a
...Read more
text at the end of the text, but not at the end of the whole text, just at the end of the visible text in the
UILabel
.

Thanks in advance.

Answer

So I've created a method which returns the current visible string height (with the size of the UITextView / UITextField or UILabel) and it's also support iOS6+, this is what I did:

- (NSUInteger)fitString:(NSString *)string intoLabel:(UILabel *)label
{
    UIFont *font           = label.font;
    NSLineBreakMode mode   = label.lineBreakMode;

    CGFloat labelWidth     = label.frame.size.width;
    CGFloat labelHeight    = label.frame.size.height;
    CGSize  sizeConstraint = CGSizeMake(labelWidth, CGFLOAT_MAX);

    if (SYSTEM_VERSION_GREATER_THAN(iOS_7))
    {
        NSDictionary *attributes = @{ NSFontAttributeName : font };
        NSAttributedString *attributedText = [[NSAttributedString alloc] initWithString:string attributes:attributes];
        CGRect boundingRect = [attributedText boundingRectWithSize:sizeConstraint options:NSStringDrawingUsesLineFragmentOrigin context:nil];
        {
            if (boundingRect.size.height > labelHeight)
            {
                NSUInteger index = 0;
                NSUInteger prev;
                NSCharacterSet *characterSet = [NSCharacterSet whitespaceAndNewlineCharacterSet];

                do
                {
                    prev = index;
                    if (mode == NSLineBreakByCharWrapping)
                        index++;
                    else
                        index = [string rangeOfCharacterFromSet:characterSet options:0 range:NSMakeRange(index + 1, [string length] - index - 1)].location;
                }

                while (index != NSNotFound && index < [string length] && [[string substringToIndex:index] boundingRectWithSize:sizeConstraint options:NSStringDrawingUsesLineFragmentOrigin attributes:attributes context:nil].size.height <= labelHeight);

                return prev;
            }
        }
    }
    else
    {
        if ([string sizeWithFont:font constrainedToSize:sizeConstraint lineBreakMode:mode].height > labelHeight)
        {
            NSUInteger index = 0;
            NSUInteger prev;
            NSCharacterSet *characterSet = [NSCharacterSet whitespaceAndNewlineCharacterSet];

            do
            {
                prev = index;
                if (mode == NSLineBreakByCharWrapping)
                    index++;
                else
                    index = [string rangeOfCharacterFromSet:characterSet options:0 range:NSMakeRange(index + 1, [string length] - index - 1)].location;
            }

            while (index != NSNotFound && index < [string length] && [[string substringToIndex:index] sizeWithFont:font constrainedToSize:sizeConstraint lineBreakMode:mode].height <= labelHeight);

            return prev;
        }
    }

    return [string length];
}

Of course that SYSTEM_VERSION_GREATER_THAN(iOS_7) are both macros that I defined. You also should define your own.

Best of luck!

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