NSMutableDictionary addEntriesFromDictionary not merging dictionaries properly - ios

Question

I have a JSON response that I store as an NSMutableDictionary that looks like this:
{
"list": { "ID1", "ID2", "ID3" },
"items": {
"ID1" : { "name" : "shoe" },
"ID2" : { "name" : "pants" },
"ID3" : { "name" : "hat" }
}
}
i need to have the NSMutableDictionary add entries from any additional JSON responses, so if i receive a new response as follows:
{
"list": { "ID4", "ID5", "ID6" },
"items": {
"ID4" : { "name" : "shirt" },
"ID5" : { "name" : "tie" },
"ID6" : { "name" : "glasses" }
}
}
the updated NSMutableDictionary needs to appear as follows:
{
"list": { "ID1", "ID2", "ID3", "ID4", "ID5", "ID6" },
"items": {
"ID1" : { "name" : "shoe" },
"ID2" : { "name" : "pants" },
"ID3" : { "name" : "hat" },
"ID4" : { "name" : "shirt" },
"ID5" : { "name" : "tie" },
"ID6" : { "name" : "glasses" }
}
}
Unfortunately, when i call addEntriesFromDictionary with the additions, i get this:
{
"list": { "ID1", "ID2", "ID3" },
"items": {
"ID1" : { "name" : "shoe" },
"ID2" : { "name" : "pants" },
"ID3" : { "name" : "hat" }
}
}
"list": { "ID4", "ID5", "ID6" },
"items": {
"ID4" : { "name" : "shirt" },
"ID5" : { "name" : "tie" },
"ID6" : { "name" : "glasses" }
}
}

Answer 1

Assuming we have the same dictionaries as in your example:
let key1 = "list"
let key2 = "items"
var rec = [key1:["ID1","ID2","ID3"],
key2:["ID1":["name":"shoe"],"ID2":["name":"pants"],"ID3":["name":"hat"]]] as [String : Any]
let inc = [key1:["ID4","ID5","ID6"],
key2:["ID4":["name":"shirt"],"ID5":["name":"tie"],"ID6":["name":"glasses"]]] as [String : Any]
I used the following rationale to find a solution:
... implemented this code snippet hereafter:
func merge(_ inc:[String:Any], into rec: inout [String:Any]) -> [String:Any] {
for (_, vals) in inc {
if var recKeys = rec[key1] as? [String],
var recItems = rec[key2] as? [String:[String:String]],
let incItems = inc[key2] as? [String:[String:String]] {
if let incValIds = vals as? [String] {
for id in incValIds {
if let newVal = incItems[id] {
if recKeys.contains(id) {
for (newValId, newValObj) in newVal {
guard var tab = recItems[id] else { continue }
tab[newValId] = newValObj
recItems[id] = tab
}
} else {
recKeys.append(id)
recItems[id] = newVal
}
}
}
}
rec[key1] = recKeys
rec[key2] = recItems
}
}
return rec
}
... and used this function as described hereunder to get the result defined below:
let updatedInfo = merge(inc, into: &rec)
print(updatedInfo)
You can now properly merge the two provided dictionaries as desired.