ios - 仅在布局 UIView 时发送数据源信息?
问题描述
我很难理解这一点。我之前已经能够完成这样的项目,但现在类似的方法对我不起作用。
这是问题所在:我有一个 UIPageViewController 有 4 storyViewControllers
。每个storyViewControllers
人都有一个习惯containerView
。我想UIViews
在containerView
. 我正在dataSource
从视图控制器发送或“n”。但是,我无法在容器视图上正确布置子视图。
本质上我想知道何时从视图控制器发送数据源信息。显然,我想在添加自定义容器视图后发送它。
我正在使用viewDidLayoutSubviews
. 这使它工作。但是,我认为这不是正确的方法。现在,每次视图控制器布置子视图时,都会调用我的委托。
我已经尝试过这样做,viewDidLoad()
但这也不起作用。
这行得通。但就是好像不太对。我的storyViewController
代码
override func viewDidLoad() {
super.viewDidLoad()
segmentContainerView = ATCStorySegmentsView()
view.addSubview(segmentContainerView)
configureSegmentContainerView()
segmentContainerView.translatesAutoresizingMaskIntoConstraints = false
}
override func viewDidLayoutSubviews() {
segmentContainerView.delegate = self
DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) {
self.segmentContainerView.startAnimation() // I am also animating these views that are laid on the containerView. Doing them here starts the animation randomly whenever I scroll through the UIPageController
}
}
在containerView
:
var delegate: ATCSegmentDataSource? {
didSet {
addSegments()
}
}
private func addSegments() {
let numberOfSegment = delegate?.numberOfSegmentsToShow()
guard let segmentQuantity = numberOfSegment else { return }
layoutIfNeeded()
setNeedsLayout()
for i in 0..<segmentQuantity {
let segment = Segment()
addSubview(segment.bottomSegment)
addSubview(segment.topSegment)
configureSegmentFrame(index: i, segmentView: segment)
segmentsArray.append(segment)
}
}
private func configureSegmentFrame(index: Int, segmentView: Segment) {
let numberOfSegment = delegate?.numberOfSegmentsToShow()
guard let segmentQuantity = numberOfSegment else { return }
let widthOfSegment : CGFloat = (self.frame.width - (padding * CGFloat(segmentQuantity - 1))) / CGFloat(segmentQuantity)
let i = CGFloat(index)
let segmentFrame = CGRect(x: i * (widthOfSegment + padding), y: 0, width: widthOfSegment, height: self.frame.height)
segmentView.bottomSegment.frame = segmentFrame
segmentView.topSegment.frame = segmentFrame
segmentView.topSegment.frame.size.width = 0
}
这按应有的方式工作。但是当我滚动 UIPageViewController 时,动画并不总是从头开始。因为它依赖于布局子视图。有时,如果我慢慢滚动页面控制器,那么子视图会再次布局,并且动画从开始开始。其他时候,当视图已经加载时,动画从我遗漏的地方开始。
问题我想知道将数据源从视图控制器发送到 containerView 的最佳方式是什么?该数据源是生成要添加到 containerView 上的视图数量所需要的。
这是我得到的结果,如果我从viewDidLayoutSubviews
. 我今天早些时候问了另一个问题,其中列出了我用来发送数据源的其他方法。也看一下:Not able to layout Subviews on a custom UIView in Swift
解决方案
这是一个非常基本的例子......
它有:
- 一个
Segment: UIView
包含“bottomSegment”和“topSegment”的子类 - 带有 a 的
ATCStorySegmentsView: UIView
子类UIStackView
来布局所需的段数 - 一个在其视图顶部
StoryViewController: UIViewController
添加的子类,ATCStorySegmentsView
然后告诉该视图对第一段进行动画处理viewDidAppear()
class Segment: UIView {
let topSegment: UIView = {
let v = UIView()
v.translatesAutoresizingMaskIntoConstraints = false
v.backgroundColor = .white
return v
}()
let bottomSegment: UIView = {
let v = UIView()
v.translatesAutoresizingMaskIntoConstraints = false
v.backgroundColor = .gray
return v
}()
var startConstraint: NSLayoutConstraint = NSLayoutConstraint()
var endConstraint: NSLayoutConstraint = NSLayoutConstraint()
override init(frame: CGRect) {
super.init(frame: frame)
commonInit()
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
func commonInit() -> Void {
addSubview(bottomSegment)
addSubview(topSegment)
// start constraint has width of Zero
startConstraint = topSegment.widthAnchor.constraint(equalTo: bottomSegment.widthAnchor, multiplier: 0.0)
// end constraint has width of bottomSegment
endConstraint = topSegment.widthAnchor.constraint(equalTo: bottomSegment.widthAnchor, multiplier: 1.0)
NSLayoutConstraint.activate([
// bottomSegment constrained to all 4 sides
bottomSegment.topAnchor.constraint(equalTo: topAnchor),
bottomSegment.bottomAnchor.constraint(equalTo: bottomAnchor),
bottomSegment.leadingAnchor.constraint(equalTo: leadingAnchor),
bottomSegment.trailingAnchor.constraint(equalTo: trailingAnchor),
// topSegment constrained top, bottom and leading
topSegment.topAnchor.constraint(equalTo: topAnchor),
topSegment.bottomAnchor.constraint(equalTo: bottomAnchor),
topSegment.leadingAnchor.constraint(equalTo: leadingAnchor),
// activate topSegemnt width constraint
startConstraint,
])
}
func showTopSegment() -> Void {
// deactivate startConstraint
startConstraint.isActive = false
// activate endConstraint
endConstraint.isActive = true
}
}
protocol ATCSegmentDataSource {
func numberOfSegmentsToShow() -> Int
}
class ATCStorySegmentsView: UIView {
let theStackView: UIStackView = {
let v = UIStackView()
v.translatesAutoresizingMaskIntoConstraints = false
v.axis = .horizontal
v.alignment = .fill
v.distribution = .fillEqually
v.spacing = 4
return v
}()
var segmentsArray: [Segment] = [Segment]()
var delegate: ATCSegmentDataSource? {
didSet {
addSegments()
}
}
override init(frame: CGRect) {
super.init(frame: frame)
commonInit()
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
func commonInit() -> Void {
addSubview(theStackView)
NSLayoutConstraint.activate([
// constrain stack view to all 4 sides
theStackView.topAnchor.constraint(equalTo: topAnchor),
theStackView.bottomAnchor.constraint(equalTo: bottomAnchor),
theStackView.leadingAnchor.constraint(equalTo: leadingAnchor),
theStackView.trailingAnchor.constraint(equalTo: trailingAnchor),
])
}
private func addSegments() {
let numberOfSegment = delegate?.numberOfSegmentsToShow()
guard let segmentQuantity = numberOfSegment else { return }
// add desired number of Segment subviews to teh stack view
for _ in 0..<segmentQuantity {
let seg = Segment()
seg.translatesAutoresizingMaskIntoConstraints = false
theStackView.addArrangedSubview(seg)
segmentsArray.append(seg)
}
}
func startAnimation() -> Void {
// this will animate changing the topSegment's width
self.segmentsArray.first?.showTopSegment()
UIView.animate(withDuration: 1.5, animations: {
self.layoutIfNeeded()
})
}
}
class StoryViewController: UIViewController, ATCSegmentDataSource {
let segmentContainerView: ATCStorySegmentsView = ATCStorySegmentsView()
override func viewDidLoad() {
super.viewDidLoad()
view.backgroundColor = .red
view.addSubview(segmentContainerView)
segmentContainerView.translatesAutoresizingMaskIntoConstraints = false
NSLayoutConstraint.activate([
// constrain segmentContainerView to top (safe-area) + 20-pts "padding",
segmentContainerView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor, constant: 20.0),
// leading and trailing with "padding" of 20-pts
segmentContainerView.leadingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leadingAnchor, constant: 20.0),
segmentContainerView.trailingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.trailingAnchor, constant: -20.0),
// constrain height to 10-pts
segmentContainerView.heightAnchor.constraint(equalToConstant: 10.0),
])
// set the delegate
segmentContainerView.delegate = self
}
override func viewDidAppear(_ animated: Bool) {
segmentContainerView.startAnimation()
}
func numberOfSegmentsToShow() -> Int {
return 3
}
}
结果(当视图出现时,白色条在灰色条上显示动画):
有 5 段:
请注意,由于设计了自动布局,它还处理大小更改,例如当设备旋转时:
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