如何以编程方式通过约束在其他两个视图之间和下方添加居中视图？ Swift

Question

如何在 ratingLabel 和 rateButton 下的距离中心添加 bestChoiceImage？
为什么，当我使用 print(anysubview.center.x) 时它 = 0.0，但在 Simulator 中一切都留在原位？

/activate inside viewWillappear

    let viewHeight = self.view.frame.height
    let viewWidth = self.view.frame.width

    NSLayoutConstraint.activate([

        reebokClassic.topAnchor.constraint(equalTo: self.view.topAnchor, constant: viewHeight/12),
        reebokClassic.centerXAnchor.constraint(equalTo: self.view.centerXAnchor),

        modelName.topAnchor.constraint(equalTo: reebokClassic.bottomAnchor, constant: viewHeight/100),
        modelName.centerXAnchor.constraint(equalTo: self.view.centerXAnchor),

        sneakersImage.topAnchor.constraint(equalTo: modelName.bottomAnchor, constant: viewHeight/40),
        sneakersImage.centerXAnchor.constraint(equalTo: self.view.centerXAnchor),
        sneakersImage.widthAnchor.constraint(equalToConstant: viewWidth * 0.8),
        sneakersImage.heightAnchor.constraint(equalToConstant: viewWidth * 0.8),

        segmentedController.widthAnchor.constraint(equalToConstant: viewWidth),
        segmentedController.topAnchor.constraint(equalTo: sneakersImage.bottomAnchor, constant: viewHeight/80),
        segmentedController.centerXAnchor.constraint(equalTo: self.view.centerXAnchor),
        segmentedController.heightAnchor.constraint(equalToConstant: viewHeight/23),

        lastTimeWeared.topAnchor.constraint(equalTo: segmentedController.bottomAnchor, constant: viewHeight/40),
        lastTimeWeared.leadingAnchor.constraint(equalTo: self.view.leadingAnchor, constant: viewHeight/100),
        lastTimeWeared.widthAnchor.constraint(equalToConstant: viewWidth/3),

        ratingLabel.topAnchor.constraint(equalTo: segmentedController.bottomAnchor, constant: viewHeight/40),
        ratingLabel.rightAnchor.constraint(equalTo: self.view.rightAnchor, constant: -viewHeight/50),
        ratingLabel.widthAnchor.constraint(equalToConstant: viewWidth/3),

        slipOnButton.bottomAnchor.constraint(equalTo: self.view.bottomAnchor, constant: -viewHeight/20),
        slipOnButton.trailingAnchor.constraint(equalTo: self.view.trailingAnchor, constant: -viewWidth/20),
        slipOnButton.widthAnchor.constraint(equalToConstant: viewWidth/5),
        slipOnButton.heightAnchor.constraint(equalToConstant: viewHeight/20),

        rateButton.bottomAnchor.constraint(equalTo: self.view.bottomAnchor, constant: -viewHeight/20),
        rateButton.leadingAnchor.constraint(equalTo: self.view.leadingAnchor, constant: viewWidth/20),
        rateButton.widthAnchor.constraint(equalToConstant: viewWidth/5),
        rateButton.heightAnchor.constraint(equalToConstant: viewHeight/20),

        bestChoiceImage.widthAnchor.constraint(equalToConstant: viewWidth/3),
        bestChoiceImage.heightAnchor.constraint(equalToConstant: viewWidth/3),
        bestChoiceImage.centerXAnchor.constraint(equalTo: self.view.centerXAnchor),
        bestChoiceImage.bottomAnchor.constraint(equalTo: self.view.bottomAnchor, constant:
            -(**rateButton.center.y - ratingLabel.center.y - bestChoiceImage.frame.height/2**))
    ])

Answer 1

将 ratingLabel 和 rateButton 放在容器视图（例如堆栈视图）中，并在 bestChoiceImage 和该容器视图之间进行约束。
您可能在自动布局引擎实际完成工作之前打印它。例如，尝试在 viewDidAppear 中打印它。

如何以编程方式通过约束在其他两个视图之间和下方添加居中视图？ Swift

How to add a view an centered between and under two other views by constraint programmatically? Swift

constraints

swift