父視圖根據(jù)label的高度自適應(yīng)調(diào)整：
需要設(shè)置label：
1、numberOfLines
2、preferredMaxLayoutWidth 或者 固定label的寬度
3、- (void)setContentHuggingPriority:(UILayoutPriority)priority forAxis:(UILayoutConstraintAxis)axis;
代碼如下：

- (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 = @"蘋(píng)果iOS15即將登場(chǎng)，界面設(shè)計(jì)煥然一新，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 = @"雖然官方并沒(méi)有舉行任何預(yù)熱活動(dòng)，但事實(shí)上，目前外網(wǎng)已經(jīng)傳出了諸多關(guān)于iOS15系統(tǒng)的消息。綜合來(lái)看，相比iOS14，iOS15仍是以提升體驗(yàn)為主，并不會(huì)有太多亮眼的新功能。";
}

結(jié)果如下：

image.png