how to make add see more featues in UILable if length of string is more than the number of line display in lable?

i count the require lable size using below code

CGSize expectedLabelSize = [text sizeWithFont:instructions.font 
                            constrainedToSize:instructions.frame.size
                                lineBreakMode:UILineBreakModeWordWrap];

i count the number ofline of lable using below code

 int numberofline = ceil(lable.frame.size.height / font.lineHeight);

in my case i require only 3 line on the button click the hole text display in tableview...due to modifing the cell height...

//please help me to check how to get number of characters for given font family....

![this is demo image][1] see image on following link [click to view image demo][1]