Height of UILabel

The only realiable way to calculate height of the string is this one. Use it or soon you'll find out that for some combination of string/font/width you label is not high enough.

There is solution, everything else will fail (yes, all UIKIt methods, and CTFramesetterSuggestFrameSizeWithConstraints will fail as well)

+ (CGFloat)heightForAttributedString:(NSAttributedString *)attrString forWidth:(CGFloat)inWidth
{
 CGFloat H = 0;

 // Create the framesetter with the attributed string.
 CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString( (CFMutableAttributedStringRef) attrString);

 CGRect box = CGRectMake(0,0, inWidth, CGFLOAT_MAX);

 CFIndex startIndex = 0;

 CGMutablePathRef path = CGPathCreateMutable();
 CGPathAddRect(path, NULL, box);

 // Create a frame for this column and draw it.
 CTFrameRef frame = CTFramesetterCreateFrame(framesetter, CFRangeMake(startIndex, 0), path, NULL);

 // Start the next frame at the first character not visible in this frame.
 //CFRange frameRange = CTFrameGetVisibleStringRange(frame);
 //startIndex += frameRange.length;

 CFArrayRef lineArray = CTFrameGetLines(frame);
 CFIndex j = 0, lineCount = CFArrayGetCount(lineArray);
 CGFloat h, ascent, descent, leading;

 for (j=0; j < lineCount; j++)
 {
 CTLineRef currentLine = (CTLineRef)CFArrayGetValueAtIndex(lineArray, j);
 CTLineGetTypographicBounds(currentLine, &ascent, &descent, &leading);
 h = ascent + descent + leading;
 H+=h;
 }

 CFRelease(frame);
 CFRelease(path);
 CFRelease(framesetter);

 return H;
}