i want to add only the values of 2 dictionaries - ios

Question

I have a swift code which is auto migrated from objective C to swift where is am getting an error
"Binary operator '+' cannot be applied to two 'Dictionary.Values' operands".
Because i trying to add the values of a dictionary which is not allowed. but how to add the values others wise. Below is the code where i am getting this error.
var result = cellAttrDict.values + supplHeaderAttrDict.values
override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
var i: Int
var begin = 0
var end = unionRects.count
var cellAttrDict: [AnyHashable : Any] = [:]
var supplHeaderAttrDict: [AnyHashable : Any] = [:]
var supplFooterAttrDict: [AnyHashable : Any] = [:]
var decorAttrDict: [AnyHashable : Any] = [:]
for i in 0..<unionRects.count {
if rect.intersects(unionRects[i] as! CGRect) {
begin = i * unionSize
break
}
}
i = unionRects.count - 1
while i >= 0 {
if rect.intersects(unionRects[i] as! CGRect) {
end = min((i + 1) * unionSize, allItemAttributes.count)
break
}
i -= 1
}
for i in begin..<end {
let attr = allItemAttributes[i] as? UICollectionViewLayoutAttributes
if rect.intersects(attr?.frame ?? 0 as! CGRect) {
switch attr?.representedElementCategory {
case .supplementaryView?:
if (attr?.representedElementKind == CHTCollectionElementKindSectionHeader) {
if let indexPath = attr?.indexPath, let attr = attr {
supplHeaderAttrDict[indexPath] = attr
}
} else if (attr?.representedElementKind == CHTCollectionElementKindSectionFooter) {
if let indexPath = attr?.indexPath, let attr = attr {
supplFooterAttrDict[indexPath] = attr
}
}
case .decorationView?:
if let indexPath = attr?.indexPath, let attr = attr {
decorAttrDict[indexPath] = attr
}
case .cell?:
if let indexPath = attr?.indexPath, let attr = attr {
cellAttrDict[indexPath] = attr
}
#unknown default:
break
}
}
}
var result = cellAttrDict.values + supplHeaderAttrDict.values
result = result + supplFooterAttrDict.values
result = result + decorAttrDict.values
return result as? [UICollectionViewLayoutAttributes]
}

Answer 1

Dictionary.Values is a special lightweight view to the dictionary values to avoid allocating extra memory.
To be able to concatenate multiple values you have to create regular arrays
var result = Array(cellAttrDict.values) + Array(supplHeaderAttrDict.values)
result += Array(supplFooterAttrDict.values)
result += Array(decorAttrDict.values)
return result as? [UICollectionViewLayoutAttributes]