在swift中为按钮添加约束（Apple iOS教程）

Question

我正在为iOS开发编程Apples Tutorial（章节：＆＃34;为视图添加按钮＆＃34;）。只是复制以下代码我得到了不同的结果：

import UIKit

@IBDesignable class RatingControl: UIStackView {

//MARK: Properties
private var ratingButtons = [UIButton]()

var rating = 0
@IBInspectable var starSize: CGSize = CGSize(width: 44.0, height: 44.0)
@IBInspectable var starCount: Int = 5

//MARK: Initialisation
override init(frame: CGRect) {
    super.init(frame: frame)
    setupButtons()
}
required init(coder: NSCoder) {
    super.init(coder: coder)
    setupButtons()
}

//MARK: Private Methods
private func setupButtons() {

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

        // Add constraints
        button.translatesAutoresizingMaskIntoConstraints = false
        button.heightAnchor.constraint(equalToConstant: starSize.height).isActive = true
        button.widthAnchor.constraint(equalToConstant: starSize.width).isActive = true

        // Setup the button action
        button.addTarget(self, action: #selector(RatingControl.ratingButtonTapped(button:)), for: .touchUpInside)

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

        // Add the new button to the rating button array
        ratingButtons.append(button)
}

//MARK: Button Action
func ratingButtonTapped(button: UIButton) {
    print("Button pressed ")
}

}

这些限制似乎不起作用。我的红色按钮与超级堆栈视图的大小完全相同。它不受44x44的限制。

控制台报告并非同时满足所有约束条件：

      2016-12-25 18:43:02.375251 FoodTracker[13644:1695258] [LayoutConstraints] 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:0x600000092160 UIButton:0x7ff15f40a740.width == 44   (active)>",
    "<NSLayoutConstraint:0x608000095a90 'UISV-canvas-connection' FoodTracker.RatingControl:0x7ff15f6116c0.leading == UIButton:0x7ff15f40a740.leading   (active)>",
    "<NSLayoutConstraint:0x608000095b30 'UISV-canvas-connection' H:[UIButton:0x7ff15f40a740]-(0)-|   (active, names: '|':FoodTracker.RatingControl:0x7ff15f6116c0 )>",
    "<NSLayoutConstraint:0x608000095630 'UIView-Encapsulated-Layout-Width' FoodTracker.RatingControl:0x7ff15f6116c0.width == 200   (active)>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x600000092160 UIButton:0x7ff15f40a740.width == 44   (active)>

Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.
2016-12-25 18:43:02.376266 FoodTracker[13644:1695258] [LayoutConstraints] 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:0x600000091e90 UIButton:0x7ff15f40a740.height == 44   (active)>",
    "<NSLayoutConstraint:0x608000095b80 'UISV-canvas-connection' FoodTracker.RatingControl:0x7ff15f6116c0.top == UIButton:0x7ff15f40a740.top   (active)>",
    "<NSLayoutConstraint:0x608000095c70 'UISV-canvas-connection' V:[UIButton:0x7ff15f40a740]-(0)-|   (active, names: '|':FoodTracker.RatingControl:0x7ff15f6116c0 )>",
    "<NSLayoutConstraint:0x608000095680 'UIView-Encapsulated-Layout-Height' FoodTracker.RatingControl:0x7ff15f6116c0.height == 110   (active)>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x600000091e90 UIButton:0x7ff15f40a740.height == 44   (active)>

Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.

但是，我没有为堆栈视图定义其他约束，除了上面的类。同样在Interface Builder中，大纲中的堆栈视图没有其他约束。 ＆＃39; UISV-canvas-connection＆＃39;来自？

Answer 1

在使用Apple的教程时遇到了同样的问题，并且确实犯了在垂直堆栈视图外创建水平堆栈视图的错误。

将其拖回垂直堆栈视图后，它适用于我：）