UIViewRepresentable中的UICollectionView赢得';t从一个表中滚动到一个项目
我有一个类,用于在成员变量UICollectionView中触发移动函数:UIViewRepresentable中的UICollectionView赢得';t从一个表中滚动到一个项目,uicollectionview,swiftui,Uicollectionview,Swiftui,我有一个类,用于在成员变量UICollectionView中触发移动函数: class CollectionFunctionStore : ObservableObject { //class to hold data about a UICollection and from where some functions can be triggered var collectionRef : UICollectionView? func jumpGrid(){
class CollectionFunctionStore : ObservableObject {
//class to hold data about a UICollection and from where some functions can be triggered
var collectionRef : UICollectionView?
func jumpGrid(){
if let lclCollection = collectionRef {
let ip = IndexPath(row: 15, section: 0)
lclCollection.scrollToItem(at: ip, at: .bottom, animated: false)
lclCollection.reloadData()
print("jumpGrid() was reached: ")
}
}
}
这里的单一功能“jumpGrid”会将网格反弹到第15行
此类正在swiftUI应用程序中使用,相关集合包含在UIViewRepresentable中。函数存储区和包含UICollectionView的UIViewRepresentable都与顶级内容视图中的按钮一起位于结构中
import SwiftUI
struct ContentView: View {
@ObservedObject var swiperStore = CollectionFunctionStore()
var body: some View {
return ZStack {
VStack{
CollectionAndStoreContainer(swiperStore: swiperStore)
JumpButton(swiperStore: swiperStore)
}.onAppear(perform: swiperStore.jumpGrid)
}
}
}
struct CollectionAndStoreContainer : View {
@ObservedObject var swiperStore : CollectionFunctionStore
var body: some View{
return ZStack{
CollectionViewRepresentable(swiperStoreParam: swiperStore).frame(width: 30, height: 200)
}
}
}
struct JumpButton : View {
@ObservedObject var swiperStore : CollectionFunctionStore
var body : some View{
return Button(action: {
swiperStore.jumpGrid()
}){
ZStack {
Rectangle().frame(width: 60, height: 30).foregroundColor(.orange).cornerRadius(4)
Text("j").foregroundColor(.white)
}
}
}
}
我面临的问题是:包含与顶层视图相同的函数存储的按钮可以触发滚动到项目功能,而onAppear事件可以调用该函数,它将实际打印其代码中包含的消息,但不会移动集合的内容。。。
按钮调用该函数,UICollectionView会正确响应
onAppear调用函数,但UICollectionView不移动
======一些其他信息=====
在这种情况下,我没有选择使用UIViewRepresentable,我不能使用lazyHgrid或HStacks
此外,这里还有相关UIViewRepresentable的代码
struct CollectionViewRepresentable : UIViewRepresentable {
var swiperStore : CollectionFunctionStore
typealias UIViewType = UICollectionView
init(swiperStoreParam : CollectionFunctionStore) {
swiperStore = swiperStoreParam
}
func makeUIView(context: Context) -> UICollectionView {
let layout = UICollectionViewFlowLayout()
layout.scrollDirection = .vertical
layout.itemSize = CGSize(width: 30, height: 30)
layout.sectionInset = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)
layout.minimumLineSpacing = 0
let collectionView = UICollectionView(frame: .zero, collectionViewLayout: layout)
collectionView.dataSource = context.coordinator
collectionView.delegate = context.coordinator
collectionView.register(ExtendedCell.self, forCellWithReuseIdentifier: "ExtCell")
collectionView.isScrollEnabled = true
collectionView.showsHorizontalScrollIndicator = false
collectionView.showsVerticalScrollIndicator = false
swiperStore.collectionRef = collectionView
return collectionView
}
func makeCoordinator() -> Coordinator {
return Coordinator()
}
func updateUIView(_ uiView: UICollectionView, context: Context) {
}
}
有人有什么想法吗?总体目标是让UICollectionView在它出现的一开始就滚动到一个特定的位置,所以我认为在SwiftUI中使用onAppear是最好的方式,但是由于某些原因它没有移动网格,例如在协调器中有更好的选项吗?
感谢您的帮助。我认为现在在onAppear中调用scroll to还为时过早,因为集合视图当时还没有完成构建 试一试 甚至
}.onAppear {
// with some delay, if appeared constructed with animation or async, etc.
DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) { // 0.25-0.5 sec
swiperStore.jumpGrid()
}
}
只要把它放进去,我就得到了“表达式解析为一个未使用的函数”的消息,……还有更好的生命周期事件可以使用吗?啊!,我犯了一个语法错误,我在快速更改后尝试了第一个,它似乎起了作用。告诉我,在UIViewRepresentable的协调器中有没有这样做的方法?哈哈,我自己应该得到的…有点尴尬。。。
}.onAppear {
// with some delay, if appeared constructed with animation or async, etc.
DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) { // 0.25-0.5 sec
swiperStore.jumpGrid()
}
}