父视图根据label的高度自适应调整：
需要设置label：
1、numberOfLines
2、preferredMaxLayoutWidth 或者 固定label的宽度
3、- (void)setContentHuggingPriority:(UILayoutPriority)priority forAxis:(UILayoutConstraintAxis)axis;
代码如下：

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    
    UIView *contentView = [[UIView alloc] init];
    [self.view addSubview:contentView];
    contentView.backgroundColor = [UIColor redColor];
    [contentView mas_makeConstraints:^(MASConstraintMaker *make) {
        make.center.equalTo(@0);
        make.width.equalTo(@300);
    }];

    UILabel *label1 = [[UILabel alloc] init];
    [contentView addSubview:label1];
    [label1 mas_makeConstraints:^(MASConstraintMaker *make) {
        make.top.equalTo(@20);
    //    make.centerX.equalTo(@0);
        make.left.equalTo(@50);
        make.right.equalTo(@-50);
    }];

    label1.numberOfLines = 0;
    // label.preferredMaxLayoutWidth = 200;
    [label1 setContentHuggingPriority:UILayoutPriorityRequired forAxis:UILayoutConstraintAxisHorizontal];
    label1.backgroundColor = [UIColor whiteColor];
    label1.text = @"苹果iOS15即将登场，界面设计焕然一新，比iOS14更漂亮";
    
    UILabel *label2 = [[UILabel alloc] init];
    [contentView addSubview:label2];
    [label2 mas_makeConstraints:^(MASConstraintMaker *make) {
        make.top.equalTo(label1.mas_bottom).offset(20);
        make.left.equalTo(@50);
        make.right.equalTo(@-50);
        make.bottom.equalTo(@-20);
    }];

    label2.numberOfLines = 0;
    // label.preferredMaxLayoutWidth = 200;
    [label2 setContentHuggingPriority:UILayoutPriorityRequired forAxis:UILayoutConstraintAxisHorizontal];
    label2.backgroundColor = [UIColor whiteColor];
    label2.text = @"虽然官方并没有举行任何预热活动，但事实上，目前外网已经传出了诸多关于iOS15系统的消息。综合来看，相比iOS14，iOS15仍是以提升体验为主，并不会有太多亮眼的新功能。";
}

结果如下：

image.png