以编程方式添加约束不符合优先级

下面是向superview添加视图的循环。每个子视图都是左侧的删除按钮和信息。。。。。他们坐在父视图中。。。

每个子视图都约束到上面的视图。。。并且俯视图被约束到父视图的上边缘。。全部按程序添加。

“删除”按钮将一次删除一个

一旦我为每个视图添加了一个次要的顶部约束来解释删除,那么我会得到以下结果。。。。

var horizontalConstraint1 = NSLayoutConstraint()
var horizontalConstraint2 = NSLayoutConstraint()
var verticalConstraint1 = NSLayoutConstraint()
var verticalConstraintOuter = NSLayoutConstraint()

    horizontalConstraint1 = v.leadingAnchor.constraint(equalTo: (v.superview?.leadingAnchor)!,constant:10)
    horizontalConstraint2 = v.trailingAnchor.constraint(equalTo: (v.superview?.trailingAnchor)!,constant:-10)
      if self.prevView == nil{
           verticalConstraint1 = v.topAnchor.constraint(equalTo: (v.superview?.topAnchor)!, constant: 0)
           NSLayoutConstraint.activate([horizontalConstraint1,horizontalConstraint2,verticalConstraint1 ]) 
            }else {
                 if let pv = self.prevView as? UIView {
                  verticalConstraint1 = v.topAnchor.constraint(equalTo: (pv.bottomAnchor), constant: 10)
                  verticalConstraintOuter = v.topAnchor.constraint(equalTo: (v.superview?.topAnchor)!,constant:10 )
                  verticalConstraintOuter.priority = UILayoutPriority(rawValue: 800)
                  NSLayoutConstraint.activate([horizontalConstraint1,horizontalConstraint2,verticalConstraint1,verticalConstraintOuter])
                        }
     }
       self.prevView = v