无法解释'|' 字符

Question

我需要你的帮助,因为我不明白我的自动约束是怎么回事.我的开关的限制使应用程序崩溃.当我删除它时,它工作得很好.这是我得到的错误消息:无法解释'|' 字符,因为相关视图没有超视图H:| -100- [v0(35)] |

谢谢你的帮助

这是我的代码:

class selectionCustomCell: UITableViewCell{
    var label: UILabel = {
        let attribution = UILabel()
        attribution.text = "Nom du label"
        attribution.textColor = UIColor(r: 0, g: 185, b: 255)
        attribution.lineBreakMode = NSLineBreakMode.ByWordWrapping
        attribution.numberOfLines = 0
        attribution.translatesAutoresizingMaskIntoConstraints = false
        return attribution
    }()

  var switchElement: UISwitch{
        let sL = UISwitch()
        sL.setOn(true, animated: true)
        sL.onTintColor = UIColor(r: 0, g: 185, b: 255)
        sL.tintColor = UIColor(r: 0, g: 185, b: 255)
        sL.translatesAutoresizingMaskIntoConstraints = false
        return sL
    }

    override init(style: UITableViewCellStyle, reuseIdentifier: String?) {
        super.init(style: .Default, reuseIdentifier: reuseIdentifier)
        addSubview(switchElement)
        addSubview(label)
        setupViews()
    }

    func setupViews(){
        addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|-20-[v0]|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0": label]))          
        addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|-20-[v0]", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0": label]))


        addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("H:|-100-[v0(35)]|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0": switchElement]))


        addConstraints(NSLayoutConstraint.constraintsWithVisualFormat("V:|-20-[v0(35)]", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0": switchElement]))


    }

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

}

Answer 1

注意how label和switchView声明之间的区别:label初始化为闭包的输出,它在第一次被引用时执行. switchView是计算的特性与被每次被引用时,这意味着你引用的版本调用一个getter -setupViews是不一样的,你那叫一个-addSubview先前.由于它们不属于视图层次结构,因此可视格式无效.

如果你声明switchView匹配声明label,你的代码应该按预期工作:

var switchElement: UISwitch = { // note the equal operator here
    let sL = UISwitch()
    // ...
    return sL
}() // note the invocation of the block here