UILabel visible part of text

Question

Is there a way to get the visible part of text in word wrapped UILabel? I mean exactly the last visible character?

I\'d like to make two labels rounding

Answer 1

You could use a category to extend NSString and create the method you mention

@interface NSString (visibleText)

- (NSString*)stringVisibleInRect:(CGRect)rect withFont:(UIFont*)font;

@end

@implementation NSString (visibleText)

- (NSString*)stringVisibleInRect:(CGRect)rect withFont:(UIFont*)font
{
    NSString *visibleString = @"";
    for (int i = 1; i <= self.length; i++)
    {
        NSString *testString = [self substringToIndex:i];
        CGSize stringSize = [testString sizeWithFont:font];
        if (stringSize.height > rect.size.height || stringSize.width > rect.size.width)
            break;

        visibleString = testString;
    }
    return visibleString;
}

@end

Answer 2

Here's a O(log n) method with iOS 7 APIs. Only superficially tested, please comment if you find any bugs.

- (NSRange)hp_visibleRange
{
    NSString *text = self.text;
    NSRange visibleRange = NSMakeRange(NSNotFound, 0);
    const NSInteger max = text.length - 1;
    if (max >= 0)
    {
        NSInteger next = max;
        const CGSize labelSize = self.bounds.size;
        const CGSize maxSize = CGSizeMake(labelSize.width, CGFLOAT_MAX);
        NSMutableParagraphStyle *paragraphStyle = [[NSParagraphStyle defaultParagraphStyle] mutableCopy];
        paragraphStyle.lineBreakMode = self.lineBreakMode;
        NSDictionary * attributes = @{NSFontAttributeName:self.font, NSParagraphStyleAttributeName:paragraphStyle};
        NSInteger right;
        NSInteger best = 0;
        do
        {
            right = next;
            NSRange range = NSMakeRange(0, right + 1);
            NSString *substring = [text substringWithRange:range];
            CGSize textSize = [substring boundingRectWithSize:maxSize
                                                      options:NSStringDrawingUsesLineFragmentOrigin
                                                   attributes:attributes
                                                      context:nil].size;
            if (textSize.width <= labelSize.width && textSize.height <= labelSize.height)
            {
                visibleRange = range;
                best = right;
                next = right + (max - right) / 2;
            } else if (right > 0)
            {
                next = right - (right - best) / 2;
            }
        } while (next != right);
    }
    return visibleRange;
}