删除角半径iOS上的阴影/边界线

Question

我有两个UIViews重叠，角半径。它们都有相同的颜色。我试图找出，如何防止角半径使一个稍微更暗的“边界描边”有谁知道如何防止这种情况？

var topHistoryLine : UIView
var bottomHistoryLine :UIView

    topHistoryLine.layer.clipsToBounds = topHistoryLine.bounds.width/2
    topHistoryLine.clipsToBounds = true
    bottomHistoryLine.layer.cornerRadius = bottomHistoryLine.bounds.width/2
    bottomHistoryLine.clipsToBounds = true
    topHistoryLine.layer.shadowOpacity = 0.0
    bottomHistoryLine.layer.shadowOpacity = 0.0

Example

Answer 1

View.layer.shadowOpacity = 0.0
View.layer.shadowRadius = 0.0
View.layer.shadowColor = UIColor.clear