什么是等效于 Objective-C 中的 getConstraintForFirstItem 的 swift 方法

Question

Earlier I have used getConstraintForFirstItem to retrieve particular constraints in Objective-C like

[[self.superview constraints] getConstraintForFirstItem:self andFirstAttributeis:NSLayoutAttributeBottom];

But cannot find equivalent method in swift to retrieve it and it says Value of type '[NSLayoutConstraint]' has no member 'getConstraintForFirstItem' . Any solution for this issue?

Answer 1

try this

You can use the firstItem, secondItem properties of [NSLayoutConstraint] to get the views related to the constraint.

let  getConstraints =  self.view.superview!.constraints
        for constraint in getConstraints {
            if let getFirstItem = constraint.firstItem, getFirstItem.firstAttribute == NSLayoutConstraint.Attribute.bottom{
           break
        }
      }