1.自适应宽度
前提不需要设置label的宽度
[yourLabel setContentHuggingPriority:UILayoutPriorityRequired
forAxis:UILayoutConstraintAxisHorizontal];
2.label多行自适应高度
//给一个maxWidth
label.preferredMaxLayoutWidth = width;
//设置
[label setContentHuggingPriority:UILayoutPriorityRequired
forAxis:UILayoutConstraintAxisVertical];
//设置换行
huggingPrioritylabel.numberOfLines = 0;