刪除約束iOS

Question

我嘗試刪除約束。我希望對肖像和風景有不同的限制。如果我將方向更改爲縱向，則我調用函數setupConstrainsInPortrait，反之亦然。我有兩個功能。

此功能設置縱向模式。

func setupConstrainsInPortrait() { 

    view.addSubview(myView) 

    myView.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true 
    myView.topAnchor.constraint(equalTo: view.topAnchor, constant: 50).isActive = true 
    myView.heightAnchor.constraint(equalToConstant: 300).isActive = true 
    myView.widthAnchor.constraint(equalToConstant: view.frame.size.width).isActive = true 

    view.addSubview(switchKmM) 

    switchKmM.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true 
    switchKmM.topAnchor.constraint(equalTo: myView.bottomAnchor, constant: 10).isActive = true 
    switchKmM.heightAnchor.constraint(equalToConstant: 50).isActive = true 
    switchKmM.widthAnchor.constraint(equalTo: view.widthAnchor).isActive = true 

    view.addSubview(speedLbl) 

    speedLbl.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true 
    speedLbl.topAnchor.constraint(equalTo: view.bottomAnchor, constant: -50).isActive = true 
    speedLbl.heightAnchor.constraint(equalToConstant: 50).isActive = true 
    speedLbl.widthAnchor.constraint(equalTo: view.widthAnchor).isActive = true 

} 

此功能設置橫向模式。

func setupConstrainsInLandScape() { 
    view.addSubview(myView) 

    myView.leftAnchor.constraint(equalTo: view.leftAnchor, constant: 10).isActive = true 
    myView.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true 
    myView.heightAnchor.constraint(equalToConstant: 300).isActive = true 
    myView.widthAnchor.constraint(equalToConstant: 150).isActive = true 

    view.addSubview(switchKmM) 

    switchKmM.leftAnchor.constraint(equalTo: myView.rightAnchor, constant: 30).isActive = true 
    switchKmM.topAnchor.constraint(equalTo: view.topAnchor, constant: 30).isActive = true 
    switchKmM.heightAnchor.constraint(equalToConstant: 50).isActive = true 
    switchKmM.widthAnchor.constraint(equalTo: view.widthAnchor).isActive = true 
} 

我viewWillTransition

override func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) { 
    if UIDevice.current.orientation.isLandscape { 
     print("landscape!") 
     view.backgroundColor = .green 
     setupConstrainsInLandScape() 
     self.viewWillLayoutSubviews() 


    } 
    else { 
     print("portrét") 
     view.backgroundColor = .white 
     setupConstrainsInPortrait() 
     self.viewWillLayoutSubviews() 

    } 
    super.viewWillTransition(to: size, with: coordinator) 
} 

的問題是使用這些功能，即限制（從縱向功能）以橫向模式不會被刪除

我希望有人能幫助我。 ..謝謝

Answer 1

你沒有做足夠的工作。您需要保留對您激活的所有約束的引用，以便稍後停用它們。例如，你說：

myView.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true 
myView.topAnchor.constraint(equalTo: view.topAnchor, constant: 50).isActive = true 
myView.heightAnchor.constraint(equalToConstant: 300).isActive = true 
myView.widthAnchor.constraint(equalToConstant: view.frame.size.width).isActive = true 

相反，你需要這樣說

self.myConstraints1 = [ 
    myView.centerXAnchor.constraint(equalTo: view.centerXAnchor), 
    myView.topAnchor.constraint(equalTo: view.topAnchor, constant: 50), 
    myView.heightAnchor.constraint(equalToConstant: 300), 
    myView.widthAnchor.constraint(equalToConstant: view.frame.size.width), 
] 

現在激活所有這些限制。始終以相同的方式進行。

因此，當由於方向改變而停用約束時，您可以引用它們並且可以這樣做。

Answer 2

您可以刪除您的約束使用：

myView.constraints.removeAll() 

在設置新的之前。