用途

NSLayoutDimension类是一个工厂类，方便使用API创建合适的约束。

Building Constraints

• -constraintEqualToAnchor:multiplier:
  first attribute = m * second attribute.
• -constraintEqualToAnchor:multiplier:constant
  first attribute = m * second attribute + c.
• -constraintEqualToConstant: first attribute = c.
• -constraintGreaterThanOrEqualToAnchor:multiplier:
  first attribute >= m * second attribute.
• -constraintGreaterThanOrEqualToAnchor:multiplier:constant:
  first attribute >= (m * second attribute) + c.
• -constraintGreaterThanOrEqualToConstant:
  first attribute >= c
• -constraintLessThanOrEqualToAnchor:multiplier:
  first attribute <= m * second attribute
• -constraintLessThanOrEqualToAnchor:multiplier:constant:
  first attribute <= (m * second attribute) + c
• -constraintLessThanOrEqualToConstant:
  first attribute <= c.

结束语

如果有不对的地方请及时指出，谢谢！！！