我正在使用 Swift 3。
我已按照本教程获取它,以便我可以点击表格视图单元格,该单元格将展开以显示更多信息。
我的问题是:如何做到这一点,以便在视图加载时第一个单元格展开(即用户不必单击即可看到该单元格展开),但所有其他行为保持不变(例如,如果再次单击它) ,它会解折叠)?
UITableViewCell
:
import UIKit
class ResultsCell: UITableViewCell {
@IBOutlet weak var introPara : UITextView!
@IBOutlet weak var section_heading : UILabel!
class var expandedHeight : CGFloat { get { return 200.0 } }
class var defaultHeight : CGFloat { get { return 44.0 } }
var frameAdded = false
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
override func awakeFromNib() {
super.awakeFromNib()
section_heading.translatesAutoresizingMaskIntoConstraints = false
}
func checkHeight() {
introPara.isHidden = (frame.size.height < ResultsCell.expandedHeight)
}
func watchFrameChanges() {
if(!frameAdded) {
addObserver(self, forKeyPath: "frame", options: .new, context: nil)
checkHeight()
}
}
func ignoreFrameChanges() {
if(frameAdded){
removeObserver(self, forKeyPath: "frame")
}
}
deinit {
print("deinit called");
ignoreFrameChanges()
}
// when our frame changes, check if the frame height is appropriate and make it smaller or bigger depending
override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
if keyPath == "frame" {
checkHeight()
}
}
}
UITableViewController
// class declaration and other methods above here...
override func numberOfSections(in tableView: UITableView) -> Int {
return 1
}
// number of rows in the table view
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return section_heading.count
}
// return the actual view for the cell
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let resultcell = tableView.dequeueReusableCell(withIdentifier: "resultCellTemplate", for: indexPath) as! ResultsCell
resultcell.section_heading.text = section_heading[indexPath.row]
resultcell.introPara.attributedText = contentParagraphs[indexPath.row]
return resultcell
}
// when a cell is clicked
override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
let previousIndexPath = selectedIndexPath
// the row is already selected, then we want to collapse the cell
if indexPath == selectedIndexPath {
selectedIndexPath = nil
} else { // otherwise, we expand that cell
selectedIndexPath = indexPath
}
var indexPaths : Array<IndexPath> = []
// only add a previous one if it exists
if let previous = previousIndexPath {
indexPaths.append(previous)
}
if let current = selectedIndexPath {
indexPaths.append(current)
}
// reload the specific rows
if indexPaths.count > 0 {
tableView.reloadRows(at: indexPaths, with: .automatic)
}
}
override func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
(cell as! ResultsCell).watchFrameChanges()
}
override func tableView(_ tableView: UITableView, didEndDisplaying cell: UITableViewCell, forRowAt indexPath: IndexPath) {
(cell as! ResultsCell).ignoreFrameChanges()
}
override func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
if indexPath == selectedIndexPath {
return ResultsCell.expandedHeight
} else {
return ResultsCell.defaultHeight
}
}
所以这按预期工作。
但如何才能使第一个单元格已经展开呢?
感谢您的帮助。