Question

我希望我的按钮位于我的footerView的中心。我尝试了几种方法，但每次都失败了：

1

application = UIApplication 0x0000000131d07800
launchOptions = [UIApplicationLaunchOptionsKey : Any]?  nil 
self = App.AppDelegate  0x00000001c403ac20
storyboard (UIStoryboard)   
intialViewcontroller (UIViewController) 
barFont UIFont

使用自动布局，这会使我的按钮居中，但会打破它的宽度和高度，我将其设置为30以上。

    override func tableView(_ tableView: UITableView, viewForFooterInSection section: Int) -> UIView? {
        let footerView = UIView(frame: CGRect.zero)
        footerView.backgroundColor = UIColor(rgba: "#F9FAFB")
        let button = UIButton(frame: CGRect(x:(footerView.frame.size.width - 30) / 2, y:(footerView.frame.size.height - 30) / 2, width: 30, height: 30))            button.setImage(UIImage(named: "gen-cog"), for: .normal)
        button.addTarget(self, action: #selector(footerButtonAction), for: .touchUpInside)
        footerView.addSubview(button)
    }

3

let centerYCon = NSLayoutConstraint(item: button,
                   attribute: .centerY,
                                    relatedBy: .equal,
                                    toItem: footerView,
                                    attribute: .centerY,
                                    multiplier: 1.0,
                                    constant: 0.0);
footerView.addConstraint(centerYCon)

let centerXCon = NSLayoutConstraint(item: button,
                                        attribute: .centerX,
                                        relatedBy: .equal,
                                        toItem: footerView,
                                        attribute: .centerX,
                                        multiplier: 1.0,
                                        constant: 0.0);
footerView.addConstraint(centerXCon)
footerView.addSubview(button)

Answer 1

  button.translatesAutoresizingMaskIntoConstraints = false
  footerView.addSubview(button)

现在添加两个额外的约束。

  let widthConstraint = NSLayoutConstraint(item: button, attribute: .width, relatedBy: .equal, toItem: nil, attribute: .notAnAttribute, multiplier: 1, constant: 30)
  let heightConstraint = NSLayoutConstraint(item: button, attribute: .height, relatedBy: .equal, toItem: nil, attribute: .notAnAttribute, multiplier: 1, constant: 30)
  button.addConstraints([widthConstraint, heightConstraint])

footerView中的中心按钮

1 个答案: