ios - UIButton 约束失败，但适用于 UILabel

Question

我正在尝试向 UIView 实用地添加一个按钮。此代码适用于 UI 标签，但当将其与按钮一起使用时，约束会失败。我怎样才能做到这一点？谢谢。

let homeButton =  UIButton(frame: CGRectZero)
    homeButton.setTitle("Home", forState: .Normal)
    homeButton.titleLabel!.textAlignment = NSTextAlignment.Center
    homeButton.titleLabel!.textColor = UIColor.whiteColor()
    homeButton.titleLabel!.translatesAutoresizingMaskIntoConstraints = false
    containerView.addSubview(homeButton)

    let buttonWidthConstraint = NSLayoutConstraint(item: homeButton, attribute: .Width, relatedBy: .Equal, toItem: self.containerView, attribute: .Width, multiplier: 0.5, constant: 0)
    containerView.addConstraint(buttonWidthConstraint)
    let buttonHeightConstraint = NSLayoutConstraint(item: homeButton, attribute: .Height, relatedBy: .Equal, toItem: self.containerView, attribute: .Height, multiplier: 0.5,constant: 0)
    containerView.addConstraint(buttonHeightConstraint)

    let buttonXConstraint = NSLayoutConstraint(item: homeButton, attribute: .CenterX, relatedBy: .Equal, toItem: self.containerView, attribute: .CenterX, multiplier: 1, constant: 0)
    let buttonYConstraint = NSLayoutConstraint(item: homeButton, attribute: .CenterY, relatedBy: .Equal, toItem: self.containerView, attribute: .CenterY, multiplier: 1, constant: 0)
    containerView.addConstraint(buttonXConstraint)
    containerView.addConstraint(buttonYConstraint)

Answer 1

您应该使用homeButton.translatesAutoresizingMaskIntoConstraints = false而不是homeButton.titleLabel!.translatesAutoresizingMaskIntoConstraints = false。

因为您应该为button而不是按钮的titleLabel禁用autoresizingmask!

希望这会有所帮助:)