ios - Swift 无法满足 Jump Right In 中的约束

Question

我已经开始了 IOS Jump Right 在 swift IOS 编程简介中，我目前处于这个阶段:[图片][1]代码如下:

 button.translatesAutoresizingMaskIntoConstraints = false;
 button.heightAnchor.constraint(equalToConstant: 44.0).isActive = true
 button.widthAnchor.constraint(equalToConstant: 44.0).isActive = true

这会产生以下错误:

    Unable to simultaneously satisfy constraints.
    Probably at least one of the constraints in the following list is one you 
    don't want. 
    Try this: 
        (1) look at each constraint and try to figure out which you don't expect; 
        (2) find the code that added the unwanted constraint or constraints and fix it. 
    NSLayoutConstraint:0x604000091760 UIButton:0x7f7f95519110.width == 44   (active)
    NSLayoutConstraint:0x600000097020 'UISV-canvas-connection' FoodTracker.RatingControl:0x7f7f95412d20.leading == UIButton:0x7f7f95519110.leading   (active),
    NSLayoutConstraint:0x600000093bf0 'UISV-canvas-connection' H:[UIButton:0x7f7f95519110]-(0)-|   (active, names: '|':FoodTracker.RatingControl:0x7f7f95412d20 ),
    NSLayoutConstraint:0x600000099fa0 'UIView-Encapsulated-Layout-Width' FoodTracker.RatingControl:0x7f7f95412d20.width == 200   (active)


Will attempt to recover by breaking constraint 
NSLayoutConstraint:0x604000091760 UIButton:0x7f7f95519110.width == 44   (active)

这是在链接到水平堆栈 View 的“自定义”类中，我尝试将 self.autoresizeSubviews 设置为 false。设置 self.translateAutoresizingMaskIntoConstraints = false 确实会消除错误，但堆栈 View 的 x,y 位置默认为 0,0。如果是这样的话，怎么会出现约束冲突:

 button.translatesAutoresizingMaskIntoConstraints = false;

删除按钮上的所有约束。

编辑，完整代码:

class RatingControl: UIStackView {

//MARK: init
override init(frame: CGRect) {
    super.init(frame: frame)
    setupButtons()
}

required init(coder: NSCoder) {
    super.init(coder: coder)
    setupButtons()
}

//MARK: Actions

func ratingButtonTapped(button: UIButton) {
    print("HELLO WORLD!");
}

//MARK: private methods

private func setupButtons() {

    // Create the button
    let button = UIButton()
    button.backgroundColor = UIColor.red

    //self.translatesAutoresizingMaskIntoConstraints = false;




    // Add constraints

    button.translatesAutoresizingMaskIntoConstraints = false;
    button.heightAnchor.constraint(equalToConstant: 44.0).isActive = true
    button.widthAnchor.constraint(equalToConstant: 44.0).isActive = true

    // Add the button to the stack
    addArrangedSubview(button)
}

}

Answer 1

这里这种错误称为不可满足的布局。基本上，对于您定义的约束，系统无法找到尊重所有约束的有效解决方案。通过您发布的内容，我可以轻松确定这组约束:

• button.height = 44//以编程方式使用layoutAnchors定义
• button.width = 44//以编程方式定义layoutAnchors的高度

然后你还有其他基于界面构建器的约束:

• RatingControl.leading = UIButton.leading
• 我认为带有按钮和评级控件的水平堆栈 View
• RatingControl.with = 200

要避免此类错误，您需要:

• 删除一项限制。您认为正在制造冲突的人

或者 - 通过降低优先级使其成为可选约束来更改约束