UILabel visible part of text - iphone

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 the image and would like to continue the text which was out of rect for first label on the second one.
I know [NSString sizeWithFont...] but are there something reversing like [NSString stringVisibleInRect: withFont:...] ? :-)
Thank you in advance.

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;
}