单行显示的UILabel根据文字内容自动调整宽度，文字下方加下划线

//根据文字的长度，动态显示label的frame

    [self.agreeLabel setNumberOfLines:0];

    NSString *s = NSLocalizedString(@"register_agreelabel", nil);

    UIFont *font = [UIFont fontWithName:@"Arial" size:12];

    CGSize size = CGSizeMake(320,2000);

    CGSize labelsize = [s sizeWithFont:font constrainedToSize:size lineBreakMode:UILineBreakModeTailTruncation];

    [self.agreeLabel setFrame:CGRectMake((320-labelsize.width)*0.5+5,434, labelsize.width, 18)];

    self.agreeBtn.frame = self.agreeLabel.frame;

    self.gouxuanBtn.frame = CGRectMake(self.agreeLabel.frame.origin.x-26,429, 35, 29);

    //下划线

    UIImageView *imav = [[UIImageView alloc] initWithFrame:CGRectMake(0,16,self.agreeLabel.frame.size.width,1)];

    imav.backgroundColor = UICOLOR_RGB(197, 39, 98);

    [self.agreeLabel addSubview:imav];

    [imav release];