set - 当滑块用于其他任务时保持原始滑块值

Question

当滑块值用于其他用途时，我希望下面的快速代码保持宽度约束的滑块值。你可以在下面的 gif 中看到发生了什么。当滑块的值用于其他用途时，约束会发生变化。当滑块的值被考虑为其他东西时，约束不应该改变。

       import UIKit
       class ViewController: UIViewController {

var frontBox = UIButton()
var backBox = UIButton()
var selectorB = UIButton()
var slider = UISlider()
var slidermultipliera: CGFloat = 0.6
var slidermultiplierb: CGFloat = 0.6
var selctorValue = 0



// constraint we will modify when slider is changed
var backBoxWidth: NSLayoutConstraint!

// constraints we will modify when backBox is dragged
var backBoxCenterY: NSLayoutConstraint!
var backBoxLeading: NSLayoutConstraint!


var FrontBoxWidth: NSLayoutConstraint!

// constraints we will modify when backBox is dragged
var FrontBoxCenterY: NSLayoutConstraint!
var FrontBoxLeading: NSLayoutConstraint!






var tim = 50.0


override func viewDidLoad() {
    super.viewDidLoad()
    
    [backBox,selectorB,frontBox,slider].forEach{
        $0.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview($0)
        $0.backgroundColor = UIColor(
            red: .random(in: 0.0...1),
            green: .random(in: 0.9...1),
            blue: .random(in: 0.7...1),
            alpha: 1
        )
    
    }
    selectorB.setTitle("right", for: .normal)
    
    NSLayoutConstraint.activate([
 
        
        selectorB.bottomAnchor.constraint(equalTo: view.bottomAnchor),
        selectorB.leadingAnchor.constraint(equalTo: view.leadingAnchor),
        selectorB.heightAnchor.constraint(equalTo: view.heightAnchor,multiplier: 0.1),
        selectorB.widthAnchor.constraint(equalTo: view.widthAnchor,multiplier: 1),
        
        
        
        slider.bottomAnchor.constraint(equalTo: selectorB.topAnchor),
        slider.leadingAnchor.constraint(equalTo: view.leadingAnchor),
        slider.heightAnchor.constraint(equalTo: view.heightAnchor,multiplier: 0.1),
        slider.widthAnchor.constraint(equalTo: view.widthAnchor,multiplier: 1),
        
    ])

    
    // backBox Width constraint
    backBoxWidth = backBox.widthAnchor.constraint(equalTo: view.widthAnchor, multiplier: 0.2)
    
    // backBox CenterY constraint
    backBoxCenterY = backBox.centerYAnchor.constraint(equalTo: view.centerYAnchor)
    
    // backBox Leading constraint
    backBoxLeading = backBox.leadingAnchor.constraint(equalTo: self.view.leadingAnchor, constant: CGFloat(200))
    
    
    // backBox Width constraint
    FrontBoxWidth = frontBox.widthAnchor.constraint(equalTo: view.widthAnchor, multiplier: 0.2)
    
    // backBox CenterY constraint
    FrontBoxCenterY = frontBox.centerYAnchor.constraint(equalTo: view.centerYAnchor)
    
    // backBox Leading constraint
    FrontBoxLeading = frontBox.leadingAnchor.constraint(equalTo: self.view.leadingAnchor, constant: CGFloat(tim))
    
    
    
    slider.setValue(Float(0.5), animated: false)
    
    
    NSLayoutConstraint.activate([

        // backBox Height is constant
        backBox.heightAnchor.constraint(equalTo: view.heightAnchor,multiplier: 0.5),
        
        backBoxWidth,
        backBoxLeading,
        backBoxCenterY,
        
        frontBox.heightAnchor.constraint(equalTo: view.heightAnchor,multiplier: 0.3),
        
        FrontBoxWidth,
        FrontBoxCenterY,
        FrontBoxLeading,
        
    ])
    

    
 
 
    
    
    selectorB.addTarget(self, action: #selector(press), for: .touchDown)

    slider.addTarget(self, action: #selector(increase), for: .valueChanged)

    
}






@objc func press(){
    selctorValue = selctorValue == 0 ? 1 : 0
    
    if selctorValue == 1{

        backBoxWidth.isActive = false
        selectorB.setTitle("left", for: .normal)
    }
    else {

        FrontBoxWidth.isActive = false
        backBoxWidth.isActive = true
        selectorB.setTitle("right", for: .normal)
    
    }

    
}

@objc func increase() {
    
    
    
    if selctorValue == 1{
        
        
        slidermultipliera = CGFloat(slider.value)

        // update backBox Width constraint
        FrontBoxWidth.isActive = false
        FrontBoxWidth = frontBox.widthAnchor.constraint(equalTo: view.widthAnchor, multiplier: slidermultipliera)
        FrontBoxWidth.isActive = true
    }
    else {
        
        slidermultiplierb = CGFloat(slider.value)

        // update backBox Width constraint
        backBoxWidth.isActive = false
        backBoxWidth = backBox.widthAnchor.constraint(equalTo: view.widthAnchor, multiplier: slidermultiplierb)
        backBoxWidth.isActive = true
        
        
    }
    
    
    
    
   
    
}


  }

标签： setsliderconstraintsdidset

Answer 1

我从来没有弄乱过 Swift，但似乎当您单击其中一个框时，您应该能够根据您刚刚单击的框的宽度设置滑块值，然后再激活该框。

我猜它会发生在你的@objc func press()函数中。尝试使两个框都处于非活动状态，然后调用slider.setValue()并激活刚刚单击的框。

抱歉，我不能给你工作代码，但希望这会有所帮助。