[英]Add buttons to UIScrollView Swift 5 programmatically
我試圖以編程方式在網格中添加許多按鈕,其中行數超過屏幕大小,所以我希望它們在 UIScrollView 中。
我的最小工作示例如下:
class ViewController: UIViewController {
//center label and down a bit
let label = UILabel(frame: CGRect(x: UIScreen.main.bounds.width/2 - 100, y: 50, width: 200, height: 200))
// start scroll view underneath label (why not y: 250?)
let scrollView = UIScrollView(frame: CGRect(x: 0, y: 50, width: UIScreen.main.bounds.width, height: UIScreen.main.bounds.height))
override func viewDidLoad() {
super.viewDidLoad()
// add label to view
self.view.addSubview(label)
// add Scrollview
self.view.addSubview(scrollView)
// uncommenting the following also doesn't work
//scrollView.contentSize = CGSize(width: UIScreen.main.bounds.width, height: 4000)
// add buttons to scroll view in 5x21 grid
var idx = 1
for row in 0...20 {
for col in 0...4 {
let button = UIButton(frame: CGRect(x: col*50, y: row*50 + 200, width: 50, height: 50))
button.backgroundColor = .gray
button.setTitle("\(idx)", for: .normal)
button.addTarget(self, action: #selector(buttonAction), for: .touchUpInside)
// add button to scroll view
scrollView.addSubview(button)
idx += 1
}
}
}
@objc func buttonAction(sender: UIButton!) {
label.text = sender.title(for: .normal)
}
}
不幸的是,滾動不起作用。 即使我明確設置了更大的垂直內容大小(請參閱注釋行) //scrollView.contentSize
我想知道它是否與為固定按鈕設置 x 和 y 值有關? 但是,我還能如何在網格中對齊它們?
那么,如何在獲得工作 ScrollView 的同時獲得我想要的按鈕對齊方式?
我對集合視圖做了同樣的事情,它是滾動視圖的子類,它可以滿足您在行/列方面的需求。
此外,要管理滾動視圖的觸摸,您必須為滾動視圖實現 UIScrollViewDelegate,特別是要區分觸摸和滾動,否則最終可能會出現不可預測的行為。
你真的應該使用自動布局!!!
到目前為止,將按鈕(或任何視圖)添加到滾動視圖的最簡單方法 - 在您要求的網格布局中 - 並讓它自動確定滾動區域是使用堆棧視圖。
這是一個快速示例:
class ViewController: UIViewController {
let label = UILabel()
let scrollView = UIScrollView()
override func viewDidLoad() {
super.viewDidLoad()
// start with some text in the label
label.text = "Tap a button"
// center the text in the label
label.textAlignment = .center
// so we can see the frames
label.backgroundColor = .yellow
scrollView.backgroundColor = UIColor(white: 0.9, alpha: 1.0)
// create a vertical stack view to hold the rows of buttons
let verticalStackView = UIStackView()
verticalStackView.axis = .vertical
// we're going to use auto-layout
label.translatesAutoresizingMaskIntoConstraints = false
scrollView.translatesAutoresizingMaskIntoConstraints = false
verticalStackView.translatesAutoresizingMaskIntoConstraints = false
// add label to view
self.view.addSubview(label)
// add Scrollview to view
self.view.addSubview(scrollView)
// add stack view to scrollView
scrollView.addSubview(verticalStackView)
// now let's create the buttons and add them
var idx = 1
for row in 0...20 {
// create a "row" stack view
let rowStack = UIStackView()
// add it to the vertical stack view
verticalStackView.addArrangedSubview(rowStack)
for col in 0...4 {
let button = UIButton()
button.backgroundColor = .gray
button.setTitle("\(idx)", for: .normal)
button.addTarget(self, action: #selector(buttonAction), for: .touchUpInside)
// add button to row stack view
rowStack.addArrangedSubview(button)
// buttons should be 50x50
NSLayoutConstraint.activate([
button.widthAnchor.constraint(equalToConstant: 50.0),
button.heightAnchor.constraint(equalToConstant: 50.0),
])
idx += 1
}
}
// finally, let's set our constraints
// respect safe-area
let safeG = view.safeAreaLayoutGuide
NSLayoutConstraint.activate([
// constrain label
// 50-pts from top
// 80% of the width
// centered horizontally
label.topAnchor.constraint(equalTo: safeG.topAnchor, constant: 50.0),
label.widthAnchor.constraint(equalTo: safeG.widthAnchor, multiplier: 0.8),
label.centerXAnchor.constraint(equalTo: safeG.centerXAnchor),
// constrain scrollView
// 50-pts from bottom of label
// Leading and Trailing to safe-area with 8-pts "padding"
// Bottom to safe-area with 8-pts "padding"
scrollView.topAnchor.constraint(equalTo: label.bottomAnchor, constant: 50.0),
scrollView.leadingAnchor.constraint(equalTo: safeG.leadingAnchor, constant: 8.0),
scrollView.trailingAnchor.constraint(equalTo: safeG.trailingAnchor, constant: -8.0),
scrollView.bottomAnchor.constraint(equalTo: safeG.bottomAnchor, constant: -8.0),
// constrain vertical stack view to scrollView Content Layout Guide
// 8-pts all around (so we have a little "padding")
verticalStackView.topAnchor.constraint(equalTo: scrollView.contentLayoutGuide.topAnchor, constant: 8.0),
verticalStackView.leadingAnchor.constraint(equalTo: scrollView.contentLayoutGuide.leadingAnchor, constant: 8.0),
verticalStackView.trailingAnchor.constraint(equalTo: scrollView.contentLayoutGuide.trailingAnchor, constant: -8.0),
verticalStackView.bottomAnchor.constraint(equalTo: scrollView.contentLayoutGuide.bottomAnchor, constant: -8.0),
])
}
@objc func buttonAction(sender: UIButton!) {
label.text = sender.title(for: .normal)
}
}
這是結果:
然后我們將向下滾動並點擊另一個按鈕:
如果你想要按鈕之間的間距,你可以在viewDidLoad()
的末尾添加這樣的東西:
// suppose we want 8-pts spacing between the buttons?
verticalStackView.spacing = 8.0
verticalStackView.arrangedSubviews.forEach { v in
if let stack = v as? UIStackView {
stack.spacing = 8.0
}
}
現在它看起來像這樣:
如果您希望按鈕網格水平居中,或者如果您希望調整間距(或按鈕大小)以適應,有幾種不同的方法可以做到這一點......您沒有在問題中描述您的最終目標,但這應該是一個很好的起點。
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