将约束添加到自定义tableviewcell的最佳位置在哪里? [英] Where is the best place to add constraints to custom tableviewcells?

问题描述

我知道添加约束的最佳位置是viewDidLoad，但是对于自定义视图(尤其是自定义单元格)，我想将所有这些布局详细信息隐藏起来而不暴露给它的控制器.而且我不希望VC向其视图发送消息，因为它对耦合最有帮助，这是我最讨厌的.因此，我应该在init方法或layoutSubview或其他内容中添加约束?

I know the best place to add constraints is viewDidLoad, but for a custom view, especially for custom cells, I'd like to hide all these layout details to itself, without exposed to its controller. And I don't want VC to send message to its view, because it contributes a little to coupling, which I hate most.So where should I add constraints, in the init method or layoutSubview, or something else?

推荐答案

如果不使用情节提要，那么添加约束的最佳位置是UITableViewCell的init方法:

If not using storyboards, I would say the best place to add your constraints is in the init method of UITableViewCell:

class CustomTableViewCell : UITableViewCell {

    lazy var subview: UIView = {
        let view = UIView()
        view.backgroundColor = .orange
        view.translatesAutoresizingMaskIntoConstraints = false
        return view
    }()

    override init(style: UITableViewCellStyle, reuseIdentifier: String?) {
        super.init(style: style, reuseIdentifier: reuseIdentifier)

        contentView.addSubview(subview)
        NSLayoutConstraint.activate([
            subview.leadingAnchor.constraint(equalTo: contentView.leadingAnchor),
            subview.trailingAnchor.constraint(equalTo: contentView.trailingAnchor),
            subview.topAnchor.constraint(equalTo: contentView.topAnchor),
            subview.bottomAnchor.constraint(equalTo: contentView.bottomAnchor),
            subview.heightAnchor.constraint(equalToConstant: 230.0)
        ])
    }

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

}

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