計算Label的高度

ios7：

CGSize size2 = [lable1.text sizeWithFont:[UIFont systemFontOfSize:17] constrainedToSize:CGSizeMake(168, 20000.0f)];

NSLog(@"label高度:%f",size2.height);

ios8：

NSDictionary *attributes =@{NSFontAttributeName:[UIFontsystemFontOfSize:17]};

    CGSize textSize = [lable1.textboundingRectWithSize:CGSizeMake(168,2000) options:NSStringDrawingUsesLineFragmentOriginattributes:attributes context:nil].size;

NSLog(@"label高度:%f",textSize.height);