如何获取可变label的size

获取可变的label的size

NSString *text =@"天天开心";

  UIFont *textFont = [UIFont systemFontOfSize:13.0];

  CGSize  size = CGSizeMake(MAXFLOAT,MAXFLOAT);// 实际的 w&H <= MAXFLOAT

    NSDictionary *arrt =@{NSFontAttributeName:font};

    CGSize frameSize = [textboundingRectWithSize:size options:NSStringDrawingUsesLineFragmentOriginattributes:arrt context:nil].size;