UIButtons没有坚持UIView边缘

Question

嗨，谢谢你。我试图将两个UIButtons绑定到UIViewController view，如下所示：

首先声明它们：

fileprivate var deleteButton: UIButton = UIButton(type: .system)
fileprivate var addButton: UIButton = UIButton(type: .system)

接下来的设置：

private func setupButtons() {

    deleteButton.setTitle("Delete", for: .normal)
    addButton.setTitle("Add", for: .normal)

    deleteButton.sizeToFit()
    addButton.sizeToFit()

    deleteButton.alpha = 1
    addButton.alpha = 1

    view.addSubview(deleteButton)
    view.addSubview(addButton)

    view.addConstraint(NSLayoutConstraint(item: deleteButton,
                                          attribute: .leading,
                                          relatedBy: .equal,
                                          toItem: view,
                                          attribute: .leading,
                                          multiplier: 1.0,
                                          constant: 0))

    view.addConstraint(NSLayoutConstraint(item: deleteButton,
                                          attribute: .bottom,
                                          relatedBy: .equal,
                                          toItem: view,
                                          attribute: .bottom,
                                          multiplier: 1.0,
                                          constant: 0))

    view.addConstraint(NSLayoutConstraint(item: addButton,
                                          attribute: .trailing,
                                          relatedBy: .equal,
                                          toItem: view,
                                          attribute: .trailing,
                                          multiplier: 1.0,
                                          constant: 0))

    view.addConstraint(NSLayoutConstraint(item: addButton,
                                          attribute: .bottom,
                                          relatedBy: .equal,
                                          toItem: view,
                                          attribute: .bottom,
                                          multiplier: 1.0,
                                          constant: 0))

}

但是运行模拟器会将左侧的两个UIButton粘贴在一起，默认的CGRect帧分配给它们。

你可能知道我做错了什么？我觉得我很接近，但也许它与重新绘制视图有关？

Answer 1

您应该将translatesAutoresizingMaskIntoConstraints设置为false

// before activate constraint

deleteButton.translatesAutoresizingMaskIntoConstraints = false
addButton.translatesAutoresizingMaskIntoConstraints = false

此外，您必须设置isActive = true，而不是使用addConstraint方法