使用自动布局使UIView全屏显示

我开始使用autolayout，我的UIViewController的self.view不再占据iPhone 6或iPhone 6plus的整个屏幕。UIView的大小为size=推断

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我在约束下查看了VC的主视图，约束编辑器不允许我选择视图的顶部、左侧、右侧和底部到窗口边缘的距离为0,0,0,0。

我创建了一个函数，在UIView下添加一个白色遮罩（如果您是UIView的子类）

func addBackgroundMask(){
    backgroundMask = UIView()
    backgroundMask?.backgroundColor = UIColor(red: 1.0, green: 1.0, blue: 1.0, alpha: 0.6)
    backgroundMask?.setTranslatesAutoresizingMaskIntoConstraints(false)

    let topConstraint = NSLayoutConstraint(item: backgroundMask!, attribute:NSLayoutAttribute.Top, relatedBy:NSLayoutRelation.Equal, toItem:superview, attribute:NSLayoutAttribute.Top, multiplier:1.0, constant:0.0)

    let bottomConstraint = NSLayoutConstraint(item: backgroundMask!, attribute:NSLayoutAttribute.Bottom, relatedBy:NSLayoutRelation.Equal, toItem:superview, attribute:NSLayoutAttribute.Bottom, multiplier:1.0, constant:0.0)

    let leftConstraint = NSLayoutConstraint(item: backgroundMask!, attribute:NSLayoutAttribute.Left, relatedBy:NSLayoutRelation.Equal, toItem:superview, attribute:NSLayoutAttribute.Left, multiplier:1.0, constant:0.0)

    let rightConstraint = NSLayoutConstraint(item: backgroundMask!, attribute:NSLayoutAttribute.Right, relatedBy:NSLayoutRelation.Equal, toItem:superview, attribute:NSLayoutAttribute.Right, multiplier:1.0, constant:0.0)

    superview?.insertSubview(backgroundMask!, belowSubview: self)

    superview?.addConstraint(topConstraint)
    superview?.addConstraint(bottomConstraint)
    superview?.addConstraint(leftConstraint)
    superview?.addConstraint(rightConstraint)

}