'sizeWithFont:constrainedToSize:' is deprecated: first deprecated in iOS 7.0 - Use -boundingRectWithSize:options:attributes:context:
解决方法：
NSString *myText = @"xxxxx";
将
CGSize mySize =[myText sizeWithFont:myFont constrainedToSize:CGSizeMake(200,100)];
改写成：
CGSize mySize = [myText boundingRectWithSize:CGSizeMake(200,100) options:NSStringDrawingUsesLineFragmentOrigin attributes:@{NSFontAttributeName:myFont} context:nil].size;
文章来自：http://www.cnblogs.com/tonyxu/p/4297337.html