根据Label和字体大小自适应高度

- (void)getHeightWithLabel:(UILabel *)label andFontSize:(CGFloat)size
{
    label.numberOfLines = 0;
    NSMutableAttributedString *labelString = [[NSMutableAttributedString alloc] initWithString:label.text];
    [labelString addAttribute:NSFontAttributeName value:[UIFont systemFontOfSize:size] range:NSMakeRange(0, [labelString length])];
    CGRect labelStringRect = [labelString boundingRectWithSize:CGSizeMake(label.frame.size.width, 9999) options:NSStringDrawingUsesLineFragmentOrigin context:nil];
    CGRect labelRect = label.frame;
    labelRect.size.height = labelStringRect.size.height;
    label.frame = labelRect;
    label.attributedText = labelString;
}

根据Label和字体大小自适应宽度

- (void)getWidthWithLabel:(UILabel *)label andFontSize:(CGFloat)size
{
    label.numberOfLines = 0;
    NSMutableAttributedString *labelString = [[NSMutableAttributedString alloc] initWithString:label.text];
    [labelString addAttribute:NSFontAttributeName value:[UIFont systemFontOfSize:size] range:NSMakeRange(0, [labelString length])];
    CGRect labelStringRect = [labelString boundingRectWithSize:CGSizeMake(9999, label.frame.size.height) options:NSStringDrawingUsesLineFragmentOrigin context:nil];
    CGRect labelRect = label.frame;
    labelRect.size.width = labelStringRect.size.width;
    label.frame = labelRect;
    label.attributedText = labelString;
}