自适应长度的UILabel

CGSize size = CGSizeMake(320,12); //设置最大值
nickNameLabel.numberOfLines = 1;  //设置行数
CGSize labelsize = [nickNameLabel.text sizeWithFont:nickNameLabel.font constrainedToSize:size lineBreakMode:NSLineBreakByWordWrapping];  //字符串在指定字体和约束下的size
[nickNameLabel setFrame:CGRectMake(nickNameLabel.frame.origin.x, nickNameLabel.frame.origin.y, labelsize.width, labelsize.height)];