ios-autolayout - “NSLayoutYAxisAnchor”类型的值没有成员“约束”

Question

在 Swift 4.1 和 XCode 9.3.1 中，我收到此代码错误。

 if #available(iOS 9.0, *) {
        contentView.topAnchor.constraint(equalTo: topAnchor).isActive = true
        contentView.bottomAnchor.constraint(equalTo: bottomAnchor).isActive = true
        contentView.leftAnchor.constraint(equalTo: leftAnchor).isActive = true
        contentView.rightAnchor.constraint(equalTo: rightAnchor).isActive = true
    } else {
    }

是错误

也适用于以下代码。

if #available(iOS 9.0, *) {
                btn2.widthAnchor.constraint(equalToConstant: btn2.frame.width).isActive = true
                btn2.heightAnchor.constraint(equalToConstant: btn2.frame.height).isActive = true
            } else {
                // Fallback on earlier versions
            }

我收到类似的错误

Answer 1

浏览苹果文档后，更改以下代码

if #available(iOS 9.0, *) {
    contentView.topAnchor.constraint(equalTo: topAnchor).isActive = true
    contentView.bottomAnchor.constraint(equalTo: bottomAnchor).isActive = true
    contentView.leftAnchor.constraint(equalTo: leftAnchor).isActive = true
    contentView.rightAnchor.constraint(equalTo: rightAnchor).isActive = true
} else {
}

至

if #available(iOS 9.0, *) {
        contentView.topAnchor.constraintEqual(to: topAnchor).isActive = true
        contentView.bottomAnchor.constraintEqual(to: bottomAnchor).isActive = true
        contentView.leftAnchor.constraintEqual(to: leftAnchor).isActive = true
        contentView.rightAnchor.constraintEqual(to: rightAnchor).isActive = true
    } else {
    }

这来自

if #available(iOS 9.0, *) {
            btn2.widthAnchor.constraint(equalToConstant: btn2.frame.width).isActive = true
            btn2.heightAnchor.constraint(equalToConstant: btn2.frame.height).isActive = true
        } else {
            // Fallback on earlier versions
        }

至

 if #available(iOS 9.0, *) {
                btn2.widthAnchor.constraintEqual(toConstant: btn2.frame.width).isActive = true
                btn2.heightAnchor.constraintEqual(toConstant: btn2.frame.height).isActive = true
            } else {
                // Fallback on earlier versions
            }

为我工作谢谢。