分配给创建视图的函数时不出现 var 约束
var constraints not appearing when assigned to a function that creates a view
我希望我的 swift 代码使用 var 约束来让对象添加到代码中。我在下面添加了我正在寻找的 gif。现在下面的代码可以编译,但是你可以在下面的 gif 中看到的黑色视图没有出现在下面的代码中。在我下面的代码中,黑框根本没有出现。
import UIKit
public class ViewController : UIViewController {
var slider = UISlider()
var image1Width2: NSLayoutConstraint!
var iHieght: NSLayoutConstraint!
public override func viewDidLoad() {
super.viewDidLoad()
slider.value = 0.5
slider.translatesAutoresizingMaskIntoConstraints = false
view.addSubview(slider)
slider.isUserInteractionEnabled = true
slider.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true
slider.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
slider.heightAnchor.constraint(equalTo: view.heightAnchor,multiplier: 0.1).isActive = true
slider.widthAnchor.constraint(equalTo: view.widthAnchor,multiplier: 1).isActive = true
button.frame = .init(x: self.view.bounds.midX,
y: 0,
width: 100,
height: 100)
self.view.addSubview(button)
image1Width2 = view.widthAnchor.constraint(equalTo: view.widthAnchor ,multiplier: 0.06)
iHieght = view.widthAnchor.constraint(equalTo: view.heightAnchor ,multiplier: 0.06)
slider.addTarget(self, action: #selector(increase), for: .allEvents)
}
private lazy var button: UIButton = {
let button = UIButton()
button.backgroundColor = .blue
button.setTitleColor(.white, for: .normal)
button.setTitle("add", for: .normal)
button.addTarget(self,
action: #selector(addBlackView),
for: .touchUpInside)
return button
}()
private func getBlackView() -> UIView {
let view = UIView()
view.backgroundColor = .black
image1Width2 = view.widthAnchor.constraint(equalTo: view.widthAnchor ,multiplier: 0.06)
iHieght = view.widthAnchor.constraint(equalTo: view.heightAnchor ,multiplier: 0.06)
let recognizer = UIPanGestureRecognizer(target: self, action: #selector(moveView(_:)))
view.addGestureRecognizer(recognizer)
return view
}
@objc
private func addBlackView() {
let view = getBlackView()
self.view.addSubview(view)
}
@objc
private func moveView(_ recognizer: UIPanGestureRecognizer) {
switch recognizer.state {
case .began:
print("gesture began")
case .changed:
let translation = recognizer.translation(in: self.view)
recognizer.view!.center = .init(x: recognizer.view!.center.x + translation.x,
y: recognizer.view!.center.y + translation.y)
recognizer.setTranslation(.zero, in: self.view)
default:
break
}
}
@objc func increase() {
image1Width2.constant = CGFloat(slider.value) * view.frame.size.width * 0.10
iHieght.constant = CGFloat(slider.value) * view.frame.size.width * 0.10
}
}
你在写这个 code.Mainly iOS 基本原则时犯了几个错误
请参考这个修改后的代码,修改它并得到你的结果。
class sampleViewController: UIViewController {
var image1Width2: NSLayoutConstraint!
var iHieght: NSLayoutConstraint!
override func viewDidLoad() {
super.viewDidLoad()
view.backgroundColor = .white
view.addSubview(slider)
slider.translatesAutoresizingMaskIntoConstraints = false
slider.value = 0.5
slider.isUserInteractionEnabled = true
NSLayoutConstraint.activate([
slider.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor),
slider.leadingAnchor.constraint(equalTo: view.leadingAnchor),
slider.heightAnchor.constraint(equalToConstant: 100),
slider.widthAnchor.constraint(equalTo: view.widthAnchor,multiplier: 1),
])
view.addSubview(button)
button.translatesAutoresizingMaskIntoConstraints = false
NSLayoutConstraint.activate([
button.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -16),
button.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor, constant: 16),
button.widthAnchor.constraint(equalToConstant: 100),
button.heightAnchor.constraint(equalToConstant: 80),
])
button.addTarget(self,action: #selector(addBlackView),for: .touchUpInside)
slider.addTarget(self, action: #selector(increase), for: .allEvents)
}
let slider:UISlider = {
let slider = UISlider(frame: .zero)
return slider
}()
private lazy var button: UIButton = {
let button = UIButton()
button.backgroundColor = .blue
button.setTitleColor(.white, for: .normal)
button.setTitle("add", for: .normal)
return button
}()
let blackView: UIView = {
let view = UIView()
view.backgroundColor = .black
return view
}()
@objc
private func addBlackView() {
self.view.addSubview(blackView)
blackView.translatesAutoresizingMaskIntoConstraints = false
blackView.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true
blackView.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
image1Width2 = blackView.widthAnchor.constraint(equalTo: view.widthAnchor, multiplier: 0.1)
image1Width2.isActive = true
iHieght = blackView.heightAnchor.constraint(equalTo: view.heightAnchor, multiplier: 0.1)
iHieght.isActive = true
view.layoutIfNeeded()
let recognizer = UIPanGestureRecognizer(target: self, action: #selector(moveView(_:)))
blackView.addGestureRecognizer(recognizer)
}
@objc private func moveView(_ recognizer: UIPanGestureRecognizer) {
switch recognizer.state {
case .began:
print("gesture began")
case .changed:
let translation = recognizer.translation(in: self.view)
recognizer.view!.center = .init(x: recognizer.view!.center.x + translation.x,
y: recognizer.view!.center.y + translation.y)
recognizer.setTranslation(.zero, in: self.view)
default:
break
}
}
@objc func increase() {
image1Width2.constant = CGFloat(slider.value) * view.frame.size.width * 0.10
iHieght.constant = CGFloat(slider.value) * view.frame.size.width * 0.10
}}
我希望我的 swift 代码使用 var 约束来让对象添加到代码中。我在下面添加了我正在寻找的 gif。现在下面的代码可以编译,但是你可以在下面的 gif 中看到的黑色视图没有出现在下面的代码中。在我下面的代码中,黑框根本没有出现。
import UIKit
public class ViewController : UIViewController {
var slider = UISlider()
var image1Width2: NSLayoutConstraint!
var iHieght: NSLayoutConstraint!
public override func viewDidLoad() {
super.viewDidLoad()
slider.value = 0.5
slider.translatesAutoresizingMaskIntoConstraints = false
view.addSubview(slider)
slider.isUserInteractionEnabled = true
slider.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true
slider.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
slider.heightAnchor.constraint(equalTo: view.heightAnchor,multiplier: 0.1).isActive = true
slider.widthAnchor.constraint(equalTo: view.widthAnchor,multiplier: 1).isActive = true
button.frame = .init(x: self.view.bounds.midX,
y: 0,
width: 100,
height: 100)
self.view.addSubview(button)
image1Width2 = view.widthAnchor.constraint(equalTo: view.widthAnchor ,multiplier: 0.06)
iHieght = view.widthAnchor.constraint(equalTo: view.heightAnchor ,multiplier: 0.06)
slider.addTarget(self, action: #selector(increase), for: .allEvents)
}
private lazy var button: UIButton = {
let button = UIButton()
button.backgroundColor = .blue
button.setTitleColor(.white, for: .normal)
button.setTitle("add", for: .normal)
button.addTarget(self,
action: #selector(addBlackView),
for: .touchUpInside)
return button
}()
private func getBlackView() -> UIView {
let view = UIView()
view.backgroundColor = .black
image1Width2 = view.widthAnchor.constraint(equalTo: view.widthAnchor ,multiplier: 0.06)
iHieght = view.widthAnchor.constraint(equalTo: view.heightAnchor ,multiplier: 0.06)
let recognizer = UIPanGestureRecognizer(target: self, action: #selector(moveView(_:)))
view.addGestureRecognizer(recognizer)
return view
}
@objc
private func addBlackView() {
let view = getBlackView()
self.view.addSubview(view)
}
@objc
private func moveView(_ recognizer: UIPanGestureRecognizer) {
switch recognizer.state {
case .began:
print("gesture began")
case .changed:
let translation = recognizer.translation(in: self.view)
recognizer.view!.center = .init(x: recognizer.view!.center.x + translation.x,
y: recognizer.view!.center.y + translation.y)
recognizer.setTranslation(.zero, in: self.view)
default:
break
}
}
@objc func increase() {
image1Width2.constant = CGFloat(slider.value) * view.frame.size.width * 0.10
iHieght.constant = CGFloat(slider.value) * view.frame.size.width * 0.10
}
}
你在写这个 code.Mainly iOS 基本原则时犯了几个错误 请参考这个修改后的代码,修改它并得到你的结果。
class sampleViewController: UIViewController {
var image1Width2: NSLayoutConstraint!
var iHieght: NSLayoutConstraint!
override func viewDidLoad() {
super.viewDidLoad()
view.backgroundColor = .white
view.addSubview(slider)
slider.translatesAutoresizingMaskIntoConstraints = false
slider.value = 0.5
slider.isUserInteractionEnabled = true
NSLayoutConstraint.activate([
slider.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor),
slider.leadingAnchor.constraint(equalTo: view.leadingAnchor),
slider.heightAnchor.constraint(equalToConstant: 100),
slider.widthAnchor.constraint(equalTo: view.widthAnchor,multiplier: 1),
])
view.addSubview(button)
button.translatesAutoresizingMaskIntoConstraints = false
NSLayoutConstraint.activate([
button.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -16),
button.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor, constant: 16),
button.widthAnchor.constraint(equalToConstant: 100),
button.heightAnchor.constraint(equalToConstant: 80),
])
button.addTarget(self,action: #selector(addBlackView),for: .touchUpInside)
slider.addTarget(self, action: #selector(increase), for: .allEvents)
}
let slider:UISlider = {
let slider = UISlider(frame: .zero)
return slider
}()
private lazy var button: UIButton = {
let button = UIButton()
button.backgroundColor = .blue
button.setTitleColor(.white, for: .normal)
button.setTitle("add", for: .normal)
return button
}()
let blackView: UIView = {
let view = UIView()
view.backgroundColor = .black
return view
}()
@objc
private func addBlackView() {
self.view.addSubview(blackView)
blackView.translatesAutoresizingMaskIntoConstraints = false
blackView.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true
blackView.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
image1Width2 = blackView.widthAnchor.constraint(equalTo: view.widthAnchor, multiplier: 0.1)
image1Width2.isActive = true
iHieght = blackView.heightAnchor.constraint(equalTo: view.heightAnchor, multiplier: 0.1)
iHieght.isActive = true
view.layoutIfNeeded()
let recognizer = UIPanGestureRecognizer(target: self, action: #selector(moveView(_:)))
blackView.addGestureRecognizer(recognizer)
}
@objc private func moveView(_ recognizer: UIPanGestureRecognizer) {
switch recognizer.state {
case .began:
print("gesture began")
case .changed:
let translation = recognizer.translation(in: self.view)
recognizer.view!.center = .init(x: recognizer.view!.center.x + translation.x,
y: recognizer.view!.center.y + translation.y)
recognizer.setTranslation(.zero, in: self.view)
default:
break
}
}
@objc func increase() {
image1Width2.constant = CGFloat(slider.value) * view.frame.size.width * 0.10
iHieght.constant = CGFloat(slider.value) * view.frame.size.width * 0.10
}}