当用户向下滚动时，我在0位置插入新行。但是tableview的混蛋很少。以下是我的代码。
class SearchViewController: UIViewController,UITableViewDelegate,UITableViewDataSource,UIScrollViewDelegate {
@IBOutlet weak var tableView: UITableView!
var chatItems:NSMutableArray = []
var endDraggingPoint:CGFloat = 0;
var beginDraggingPoint:CGFloat = 0;
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
chatItems = ["SearchBarCell","ChatCell"];
for value in 1...100{
chatItems.add(String(value))
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
//MARK: - Tableview delegate Methods
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int
{
return chatItems.count
}
// Row display. Implementers should *always* try to reuse cells by setting each cell's reuseIdentifier and querying for available reusable cells with dequeueReusableCellWithIdentifier:
// Cell gets various attributes set automatically based on table (separators) and data source (accessory views, editing controls)
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell
{
var cell:UITableViewCell!
var cellIdentyfier: NSString
let itemName:NSString = chatItems.object(at: indexPath.row) as! NSString;
if itemName == "SearchBarCell"
{
cellIdentyfier = "SearchBarCell"
}else if itemName == "ArchiveLabelCell" {
cellIdentyfier = "ArchiveLabelCell"
}else {
cellIdentyfier = "ChatCell"
}
cell = tableView.dequeueReusableCell(withIdentifier: cellIdentyfier as String)
if(cell == nil)
{
cell = UITableViewCell(style: UITableViewCellStyle.default,reuseIdentifier:cellIdentyfier as String)
}
return cell;
}
func scrollViewDidScroll(_ scrollView: UIScrollView)
{
print("scrollViewDidScroll: \(scrollView.contentOffset.y)");
if endDraggingPoint == 0 && scrollView.contentOffset.y <= -30 {
self.addArchiveCell(scrollView: scrollView);
}else if scrollView.contentOffset.y > 50 {
self.removeArchiveCell(scrollView: scrollView)
}
}
func removeArchiveCell(scrollView:UIScrollView) {
if chatItems.contains("ArchiveLabelCell") {
print("Removing archive cell: \(scrollView.contentOffset.y)");
chatItems.removeObject(at: 0);
tableView.deleteRows(at: [IndexPath.init(row: 0, section: 0)], with: .none)
}
}
func addArchiveCell(scrollView:UIScrollView) {
if beginDraggingPoint <= 50 {
if !chatItems.contains("ArchiveLabelCell") {
self.chatItems.insert("ArchiveLabelCell", at: 0)
print("Adding archive cell: \(scrollView.contentOffset.y)");
//self.tableView.beginUpdates()
self.tableView.insertRows(at: [IndexPath.init(row: 0, section: 0)], with: .none)
//self.tableView.endUpdates()
}
}
}
func scrollViewWillBeginDragging(_ scrollView: UIScrollView)
{
endDraggingPoint = 0
beginDraggingPoint = scrollView.contentOffset.y
}
}
有人可以告诉我为什么tableview在向下滚动并插入新行时会出现混蛋？