ios - 如何解决Unable simultaneously satisfy constraints

Question

我正在尝试自定义约束

菜单栏类:

import UIKit

class ManuBar: UIView {
    override init(frame: CGRect) {
        super.init(frame: frame)
        backgroundColor = UIColor.blueColor()
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

}

extension UIView {
    func addConstraintsWithFormat(format: String, views: UIView...) {
        var viewsDictionary = [String: UIView]()
        for (index, view) in views.enumerate() {
            let key = "v\(index)"
            view.translatesAutoresizingMaskIntoConstraints = false
            viewsDictionary[key] = view
        }

        addConstraints(NSLayoutConstraint.constraintsWithVisualFormat(format, options: NSLayoutFormatOptions(), metrics: nil, views: viewsDictionary))
    }
}

View Controller :

import UIKit

    class ViewController: UIViewController {

        override func viewDidLoad() {
            super.viewDidLoad()
            // Do any additional setup after loading the view, typically from a nib.


            setupManuBar();

        }

        let menuBar : ManuBar = {
           let mb = ManuBar()
            return mb
        }()

        private func setupManuBar(){

            view.addSubview(menuBar)

            view.addConstraintsWithFormat("H:|[v0]|",views : menuBar)
            view.addConstraintsWithFormat("V:|-16-[v0(40)]|",views : menuBar)
        }


    }

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:0x7ff891d27c70 V:|-(16)-[Tab_Menu_Bar_Programmatically.ManuBar:0x7ff891d19f30]   (Names: '|':UIView:0x7ff891d1b570 )>",
    "<NSLayoutConstraint:0x7ff891d27f40 V:[Tab_Menu_Bar_Programmatically.ManuBar:0x7ff891d19f30(40)]>",
    "<NSLayoutConstraint:0x7ff891d0fc50 V:[Tab_Menu_Bar_Programmatically.ManuBar:0x7ff891d19f30]-(0)-|   (Names: '|':UIView:0x7ff891d1b570 )>",
    "<NSLayoutConstraint:0x7ff891d1c8e0 'UIView-Encapsulated-Layout-Height' V:[UIView:0x7ff891d1b570(736)]>"
)

将尝试通过打破约束来恢复

如果您需要更多信息，请告诉我

Answer 1

您在 view.translatesAutoresizingMaskIntoConstraints = false 中忘记了 view，因此您是在单元格上而不是在各个 View 上设置 translatesAutoresizingMaskIntoConstraints。

将for循环改为

for (index, view) in views.enumerate(){
                let key = "v\(index)"
                view.translatesAutoresizingMaskIntoConstraints = false
                viewsDictionry[key] = view

            }

我也会看看 lazy loading通过添加 lazy 关键字来查看 View 。

更新:

虽然您显着更改了代码。我测试了你的第一个例子，它成功了。您现在的问题是: view.addConstraintsWithFormat("V:|-16-[v0(40)]|",views : menuBar) 您基本上是将菜单栏的高度设置了两次。您将它设置为 40 的固定高度，但您还告诉它根据 superview 进行拉伸(stretch)。顶部 16 像素 空格 + 底部 0 像素。去掉末尾的|

像这样:

 view.addConstraintsWithFormat("H:|[v0]|",views : menuBar) 
 view.addConstraintsWithFormat("V:|-16-[v0(40)]",views : menuBar)