UICollectionView标题更改

Question

我有一个UICollectionView和4个自定义UICollectionViewCells。在UICollectionView的报头中有一个UISegmentedControl。我的目标是更改标题UILabel。现在，如果分段控制值已更改，则会重新加载单元格，并且应该切换标题，但它与第一个标题重叠。我不明白为什么。

func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
if kind == UICollectionElementKindSectionHeader {
let headerView = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: "HeaderDiscoverVC", for: indexPath) as! HeaderDiscoverVC
headerView.frame = CGRect(x: 0, y: 0, width: collectionView.frame.width, height: 30)
headerView.backgroundColor = UIColor.hex("d9e2e7")
let label = UILabel(frame: CGRect(x: 16, y: 0, width: headerView.frame.width, height: 30))
switch segReusableIdentifier {
case "Reply":
label.text = "Reply"
case "Media":
label.text = "Media"
case "Likes":
label.text = "Likes"
case "Comments":
label.text = "Comments"
default:
label.text = ""
}
label.font = UIFont(name: Fonts.OpenSans_Bold, size: 16)
label.textColor = UIColor.hex("8a9da6")
headerView.addSubview(label)
return headerView
}
fatalError("Unexpected element kind")
} 

Answer 1

问题在于将标签添加到头视图的方式。

您应该将headerView.addSubview(标签(放在HeaderDiscoverVC类中。同时将颜色和字体设置为同一类。

func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
if kind == UICollectionElementKindSectionHeader {
let headerView = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: "HeaderDiscoverVC", for: indexPath) as! HeaderDiscoverVC
headerView.frame = CGRect(x: 0, y: 0, width: collectionView.frame.width, height: 30)
// MOVE THE COMMENTED LINE TO YOUR HeaderDiscoverVC
//headerView.backgroundColor = UIColor.hex("d9e2e7")
headerView.label.frame = CGRect(x: 16, y: 0, width: headerView.frame.width, height: 30)
switch segReusableIdentifier {
case "Reply":
headerView.label.text = "Reply"
case "Media":
headerView.label.text = "Media"
case "Likes":
headerView.label.text = "Likes"
case "Comments":
headerView.label.text = "Comments"
default:
headerView.label.text = ""
}
// MOVE THE COMMENTED LINES TO YOUR HeaderDiscoverVC
//label.font = UIFont(name: Fonts.OpenSans_Bold, size: 16)
//label.textColor = UIColor.hex("8a9da6")
//headerView.addSubview(label)
return headerView
}
fatalError("Unexpected element kind")
} 

尝试并分享您的结果

Answer 2

您正在以编程方式将label添加到headerView中，应在再次添加之前将其删除。dequeueReusableSupplementaryView不会删除以编程方式添加的子视图。

在您的代码中：

func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
if kind == UICollectionElementKindSectionHeader {
let headerView = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: "HeaderDiscoverVC", for: indexPath) as! HeaderDiscoverVC
headerView.frame = CGRect(x: 0, y: 0, width: collectionView.frame.width, height: 30)
headerView.backgroundColor = UIColor.hex("d9e2e7")
///// Add below code to remove all subviews first before adding any new subview programmatically 
for label in headerView.subviews {
if let mylabel = label as? UILabel {
mylabel.removeFromSuperview()
}
}
////////////////
let label = UILabel(frame: CGRect(x: 16, y: 0, width: headerView.frame.width, height: 30))
switch segReusableIdentifier {
case "Reply":
label.text = "Reply"
case "Media":
label.text = "Media"
case "Likes":
label.text = "Likes"
case "Comments":
label.text = "Comments"
default:
label.text = ""
}
label.font = UIFont(name: Fonts.OpenSans_Bold, size: 16)
label.textColor = UIColor.hex("8a9da6")
headerView.addSubview(label)
return headerView
}
fatalError("Unexpected element kind")
} 

更好的方法是将label保留在HeaderDiscoverVC中，并在代码中使用它作为：

headerView.label.text = "Your data"

通过这种方式，您不必以编程方式删除subViews。