在我的代码中，我正在更改通过Ib插座“ collectionViewHeightConstraint”链接的高度约束
每当我运行应用程序时，都会弹出错误，指出存在冲突的约束。我试图打电话给setNeedsUpdateConstraints()，但并没有真正改变。
具有讽刺意味的是，仅在初始化前三个单元格时才调用错误。但是，如果我取出setNeedsUpdateConstraints()，则每当滚动表格视图时都会弹出错误消息。
class MonthWeekTableViewCell: UITableViewCell, UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout {
@IBOutlet weak var monthLabel: UILabel!
@IBOutlet weak var dayCollectionView: UICollectionView!
@IBOutlet weak var collectionViewHeightConstraint: NSLayoutConstraint!
var monthYear: (String,String) = ("","") {
didSet {
monthLabel.text = self.monthYear.0
guard let _maxDate = DateFormat.returnNumberOfDaysInMonth(month: self.monthYear.0, year: self.monthYear.1) else {fatalError("Tuple Error")}
maxDate = _maxDate
firstDay = DateFormat.getFirstOfMonth(year: self.monthYear.1, month: self.monthYear.0)
let extra = maxDate - 36 + firstDay
if extra > 0 {
extraCalendarItem = extra
} else if extra <= -7 {
setNeedsUpdateConstraints()
collectionViewHeightConstraint.constant = 270
}
}
}
var firstDay: Int = 0 {
didSet {
dayCollectionView.reloadData()
}
}
var extraCalendarItem: Int = 0 {
didSet {
setNeedsUpdateConstraints()
collectionViewHeightConstraint.constant = 270
}
}
var dayNumber: Int = 1
var maxDate: Int = 30
override func awakeFromNib() {
super.awakeFromNib()
dayCollectionView.delegate = self
dayCollectionView.dataSource = self
dayCollectionView.register(UINib(nibName: "DayCollectionViewCell", bundle: nil), forCellWithReuseIdentifier: "DayCollectionViewCell")
dayCollectionView.translatesAutoresizingMaskIntoConstraints = false
}
func numberOfSections(in collectionView: UICollectionView) -> Int {
if extraCalendarItem > 0 {
return 6
}
return 5
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
if section == 5 {
return extraCalendarItem
}
return 7
}
func collectionView(_ collectionView: UICollectionView, willDisplay cell: UICollectionViewCell, forItemAt indexPath: IndexPath) {
let _cell = cell as! DayCollectionViewCell
if (indexPath.section == 0 && firstDay > indexPath.row + 1) || dayNumber > maxDate{
_cell.isHidden = true
} else {
_cell.dayLabel.text = String(dayNumber)
dayNumber += 1
_cell.isHidden = false
}
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "DayCollectionViewCell", for: indexPath) as! DayCollectionViewCell
return cell
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: collectionView.frame.width / 7, height: 45)
}
override func prepareForReuse() {
dayNumber = 1
extraCalendarItem = 0
updateConstraints()
}
override func updateConstraints() {
collectionViewHeightConstraint.constant = 225
super .updateConstraints()
}
}