找到uilabel中文本的位置{x，y}

I have a string coming from server which I am displaying on UILabel multiligne. It is within that string, I am identifying some particular substring. I want to place a button on that substring(button will be a subview of UILabel). For this I require substring coordinates. I went through this but I am not able to understand it. Suppose my complete string is abc, 567-324-6554, New York. I want 567-324-6554 to be displayed on button for which I need its coordinates. How can I use above link to find coordinates of substring? Thanks,I have a string coming from server which I am d