自動レイアウト制約は、constraintEqualToAnchor（）を使用して設定した後で変更する方法はありますか？

Question

私はconstraintEqualToAnchor()を使って、自動レイアウトの制約を持つビューを設定してみてください：コードの最後の行で

override func viewDidLoad() { 
    super.viewDidLoad() 

    let myView = UIView() 
    myView.backgroundColor = UIColor.orangeColor() 
    myView.translatesAutoresizingMaskIntoConstraints = false 
    view.addSubview(myView) 

    myView.leftAnchor.constraintEqualToAnchor(view.leftAnchor).active = true 
    myView.trailingAnchor.constraintEqualToAnchor(view.trailingAnchor).active = true 
    myView.topAnchor.constraintEqualToAnchor(view.topAnchor).active = true 
    myView.bottomAnchor.constraintEqualToAnchor(view.bottomAnchor).active = true 

    /******************************************/ 
    /* I try to change one of the constraints */ 
    /******************************************/ 
    myView.leftAnchor.constraintEqualToAnchor(view.rightAnchor, constant: -100).active = true 
} 

、私は、制約の1つを変更してみてください。 constraintEqualToAnchor()?を使用している場合

"<NSLayoutConstraint:0x7fb53a5180d0 H:|-(0)-[UIView:0x7fb53a5190b0](LTR) (Names: '|':UIView:0x7fb53a519240)>", 
"<NSLayoutConstraint:0x7fb53a51f660 H:[UIView:0x7fb53a519240]-(-100)-[UIView:0x7fb53a5190b0](LTR)>", 
"<NSLayoutConstraint:0x7fb53a711ee0 'UIView-Encapsulated-Layout-Width' H:[UIView:0x7fb53a519240(414)]>" 

私はそれが仕事だろうと思ったが、それはコンソールログにいくつかのエラーを与え、私はそれらを設定した後、後に制約を変更する正しい方法は何ですか？

Answer 1

新しい制約をアクティブにするときは、以前の制約を無効にする必要があります。これにより、ビューが拘束されなくなります。これを行うには、あなたのViewControllerで財産などの制約のそれぞれへの参照を格納し、新しい制約の作成およびアクティブ化する前falseに古い制約のactiveプロパティを設定します。

スウィフト2.xの：

を

class ViewController: UIViewController { 
    var leftConstraint: NSLayoutConstraint? 
    var trailingConstraint: NSLayoutConstraint? 
    var topConstraint: NSLayoutConstraint? 
    var bottomConstraint: NSLayoutConstraint? 

    override func viewDidLoad() { 
     super.viewDidLoad() 

     let myView = UIView() 
     myView.backgroundColor = UIColor.orangeColor() 
     myView.translatesAutoresizingMaskIntoConstraints = false 
     view.addSubview(myView) 

     leftConstraint = myView.leftAnchor.constraintEqualToAnchor(view.leftAnchor) 
     leftConstraint?.active = true 

     trailingConstraint = myView.trailingAnchor.constraintEqualToAnchor(view.trailingAnchor) 
     trailingConstraint?.active = true 

     topConstraint = myView.topAnchor.constraintEqualToAnchor(view.topAnchor) 
     topConstraint?.active = true 

     bottomConstraint = myView.bottomAnchor.constraintEqualToAnchor(view.bottomAnchor) 
     bottomConstraint?.active = true 

     /******************************************/ 
     /* I try to change one of the constraints */ 
     /******************************************/ 
     leftConstraint?.active = false 
     leftConstraint = myView.leftAnchor.constraintEqualToAnchor(view.rightAnchor, constant: -100) 
     leftConstraint?.active = true 
    } 
} 

---

スウィフト3構文の更新：

class ViewController: UIViewController { 
    var leftConstraint: NSLayoutConstraint? 
    var trailingConstraint: NSLayoutConstraint? 
    var topConstraint: NSLayoutConstraint? 
    var bottomConstraint: NSLayoutConstraint? 

    override func viewDidLoad() { 
     super.viewDidLoad() 

     let myView = UIView() 
     myView.backgroundColor = UIColor.orange 
     myView.translatesAutoresizingMaskIntoConstraints = false 
     view.addSubview(myView) 

     leftConstraint = myView.leftAnchor.constraint(equalTo: view.leftAnchor) 
     leftConstraint?.isActive = true 

     trailingConstraint = myView.trailingAnchor.constraint(equalTo: view.trailingAnchor) 
     trailingConstraint?.isActive = true 

     topConstraint = myView.topAnchor.constraint(equalTo: view.topAnchor) 
     topConstraint?.isActive = true 

     bottomConstraint = myView.bottomAnchor.constraint(equalTo: view.bottomAnchor) 
     bottomConstraint?.isActive = true 

     /******************************************/ 
     /* I try to change one of the constraints */ 
     /******************************************/ 
     leftConstraint?.isActive = false 
     leftConstraint = myView.leftAnchor.constraint(equalTo: view.rightAnchor, constant: -100) 
     leftConstraint?.isActive = true 
    } 
} 

ここで

Answer 2

これは、後で参照される制約cを宣言する例です。新しい一定の値を設定し、スーパービューでlayoutを呼び出します。

myView.translatesAutoresizingMaskIntoConstraints = false 

var constraints: [NSLayoutConstraint] = [ 
    myView.topAnchor.constraintEqualToAnchor(view.topAnchor), 
    myView.leftAnchor.constraintEqualToAnchor(view.leftAnchor), 
    myView.bottomAnchor.constraintEqualToAnchor(view.bottomAnchor) 
]   
let c = myView.rightAnchor.constraintEqualToAnchor(view.rightAnchor)  
constraints.append(c) 

view.addSubview(myView) 
NSLayoutConstraint.activateConstraints(constraints) 

// Some time later 
c.constant = -100 
view.layout() 

Answer 3

// method myView.topAnchor.constraintEqualToAnchor creates new one inactive anchor 
// and not returns exist with equal relationships  

// you can set identifier for any constraint in Interface Builder or code and find & update in code 
for (NSLayoutConstraint *c in [self.view constraintsAffectingLayoutForAxis:UILayoutConstraintAxisHorizontal]) 
{ 
    if (YES == [c.identifier isEqualToString:@"my.layout-constraint.id"]) 
    { 
     // Unlike the other properties, the constant can be modified 
     // after constraint creation. 
     // Setting the constant on an existing constraint performs much better 
     // than removing the constraint and adding a new one that's exactly like 
     // the old except that it has a different constant. 

     c.constant = 123; 

     // if needed 
     // [self.view setNeedsUpdateConstraints]; 

     break; 
    } 
} 

Answer 4

StackViewを変更するIF文を使用して、一例であり、セグメント化されたが、クリックしたときに表示します

if (sender as AnyObject).selectedSegmentIndex == 0{ 


     // Shrink the white view and stack view 
     heightConstraintView = containerView.heightAnchor.constraint(equalToConstant: 100) 
     heightConstraintView?.isActive = true 

     heightConstraintStackView = stackView.heightAnchor.constraint(equalToConstant: 100) 
     heightConstraintStackView?.isActive = true 
    } 

    else { 


     // Before returning back the white view and stack view DEACTIVATE teh previous constraints 
     heightConstraintView?.isActive = false 
     heightConstraintStackView?.isActive = false 

     // Returning back the white view and stack view to normal size 
     heightConstraintView = containerView.heightAnchor.constraint(equalToConstant: 200) 
     heightConstraintView?.isActive = true 

     heightConstraintStackView = stackView.heightAnchor.constraint(equalToConstant: 200) 
      heightConstraintStackView?.isActive = true 
    }