1.宽度不够时
[_label1setContentCompressionResistancePriority:UILayoutPriorityRequiredforAxis:UILayoutConstraintAxisHorizontal];
2.宽度够时
[labelsetContentHuggingPriority:UILayoutPriorityRequiredforAxis:UILayoutConstraintAxisHorizontal];
1.宽度不够时
[_label1setContentCompressionResistancePriority:UILayoutPriorityRequiredforAxis:UILayoutConstraintAxisHorizontal];
2.宽度够时
[labelsetContentHuggingPriority:UILayoutPriorityRequiredforAxis:UILayoutConstraintAxisHorizontal];