ios - 尝试添加 UIImageView 数组的约束

Question

我创建了 UIImageViews 的数组，并在里面存储了 5 个 ImageView ，没有任何约束。

lazy var albumImage: UIImageView = {
    let image = UIImage(named: "authorizationImage")
    let imageView = UIImageView(image: image)
    imageView.frame = CGRect(x: 0, y: 0, width: 50, height: 50)
    imageView.layer.cornerRadius = 10
    imageView.backgroundColor = .black
    imageView.layer.masksToBounds = true
    imageView.translatesAutoresizingMaskIntoConstraints = false
    return imageView
}()

lazy var albumImages: [UIImageView] = [albumImage, albumImage, albumImage, albumImage, albumImage]

我将它们添加到我的 UIView 中:

for row in 0...(albumImages.count-1){
    backView.addSubview(albumImages[row])
}

并尝试根据我在 UIView 之上的 UILabel 设置每个约束:

for row in 0...(albumImages.count-1){
    let distanceFromTop = ((row*30) + (row+1)*10)
    print("geez \(row) distance \(distanceFromTop)")
    albumImages[row].topAnchor.constraint(equalTo: registrationTime.bottomAnchor, constant: CGFloat(distanceFromTop)).isActive = true
    albumImages[row].leftAnchor.constraint(equalTo: backView.leftAnchor, constant: 20).isActive = true
    albumImages[row].rightAnchor.constraint(equalTo: albumImages[row].leftAnchor, constant: 30).isActive = true
    albumImages[row].heightAnchor.constraint(equalToConstant: 30).isActive = true
}

我可以在我的模拟器上看到第一个 UIImageView。然而，其他4个未显示。我在控制台中收到错误消息:

geez 0 distance 10
geez 1 distance 50
2020-08-12 17:16:38.174252+0900 WhosFan[24100:2336027] [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:0x60000167cbe0 V:[UILabel:0x7f97ae8603b0'Based on (KST) : 2020.08....']-(10)-[UIImageView:0x7f97aeb20d60]   (active)>",
    "<NSLayoutConstraint:0x6000016777f0 V:[UILabel:0x7f97ae8603b0'Based on (KST) : 2020.08....']-(50)-[UIImageView:0x7f97aeb20d60]   (active)>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x6000016777f0 V:[UILabel:0x7f97ae8603b0'Based on (KST) : 2020.08....']-(50)-[UIImageView:0x7f97aeb20d60]   (active)>

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

我检查了我是否以错误的顺序添加了 subview 。但是，一切看起来都很好:

 override func setSelected(_ selected: Bool, animated: Bool) {
    super.setSelected(selected, animated: animated)
    addSubview(backView)
    backView.addSubview(cellTitle)
    backView.addSubview(registrationTime)
    addAlbumImages()
    setupConstraints()
    // Configure the view for the selected state
}
private func setupConstraints(){
    setUpCellTitleConstraints()
    setUpRegistrationDateLabelConstraints()
    setupAlbumImagesConstraints()
}

在过去的 2 个小时里，我一直被这个问题所困扰。请，任何帮助。
这是我的模拟器的图像:

Answer 1

您在这里只创建一个 ImageView (不是 5 个!)并将相同的 ImageView 添加到数组中 5 次:

lazy var albumImages: [UIImageView] = [albumImage, albumImage, albumImage, albumImage, albumImage]

这就是为什么你所有的约束都被打破了，只显示了一个 ImageView 。只有一个 ImageView ，并且该 ImageView 的顶部 anchor 需要同时距离 registrationTime.bottomAnchor 10、50、90、130 和 170 点!
无论如何，每次将它们添加到数组时，您都应该创建一个新的 ImageView 。一种方法是制作 albumImage成一个方法， createAlbumImageView :

func createAlbumImageView() -> UIImageView {
    let image = UIImage(named: "authorizationImage")
    let imageView = UIImageView(image: image)
    imageView.frame = CGRect(x: 0, y: 0, width: 50, height: 50)
    imageView.layer.cornerRadius = 10
    imageView.backgroundColor = .black
    imageView.layer.masksToBounds = true
    imageView.translatesAutoresizingMaskIntoConstraints = false
    return imageView
}

然后可以像这样声明数组:

lazy var albumImages: [UIImageView] = [
    createAlbumImageView(),
    createAlbumImageView(),
    createAlbumImageView(),
    createAlbumImageView(),
    createAlbumImageView(),
]

您的 ImageView 似乎在一条垂直线上，间距大致相等。我不确定不等间距是否仅仅是由另一个错误引起的。如果需要等间距，您可以改为使用垂直 UIStackView .