I have a dictionary like below,
var dataSource: [String: String] = ["FirstName": "Austin",
"ListName": "Michael",
"Address": "Street Address",
"City": "Chennai"]
I want to populate these values in a UITableView, so I tried to get all the keys from Dictionary to an Array like below,
let dataArray = Array(dataSource.keys)
I got the output as [String] like,
["LastName", "FirstName", "City", "Address"]
The problem is, the order of the keys has changed, I want the array in the same order as dictionary has.
Can you anyone help?
Use plain dictionary as tableview datasource is bad idea.
However Dictionary can not be sorted. So it doesn't matter in what order you add your keys-values to the dictionary.
If you need sorted then use array of dictionary instead.
You should use models instead of plain dictionary that is easy to maintain :]
like
struct User {
var firstName:String?
var lastName:String?
var address:String?
var city:String?
}
Related
I m mapping data that come from service with using dictionary [String: String]. I collect them dictionary array. For example, if their parent ids are the same, I want to add their values by array value.
["ParentId": "1","Value": "["Giyim","Aksesuar","Ayakkabı"]"]
It is also the reason I don't know parent id sometimes on the left sometimes on the right in photo
Here is my code and its output.
struct Categories {
let parentId: String
let values: [String]
}
for result in results {
if result?.parentCategoryId != "" {
for docId in self.docIds {
if result?.parentCategoryId == docId {
//print(result?.name)
var values = [String]()
values.append(result?.name ?? "")
self.newCat.append(Categories(parentId: docId, values: values))
}
}
}
}
Problem
As far as I understand from the description you want to map some service data structure to a dictionary where key is parentId and value is an array of some items referred to parentId.
I believe your problem comes from a misunderstanding of the concept of dictionary as a data structure.
[String: String] is dictionary where keys and their associated values are of String type. For example:
["firstKey": "firsthValue", "secondKey": "secondValue", ...]
That means you cannot store associated values of String and Array types in the same dictionary, as you already told the compiler you would like to store only strings.
It is also the reason I don't know parent id sometimes on the left sometimes on the right in photo
This is because key-value pairs are stored in the dictionary without order. This is how dictionaries work :) I'd strongly recommend reading some short official materials to get used to them.
New Swift 5.4 version has a new OrderedDictionary data structure, where keys are ordered, but there is absolutely 100500% no reason to use it for your problem*
Possible solutions
In your case i would suggest either use some struct:
struct SomeData {
let parentID: Int
var values: [String]
}
var storage: [SomeData] // alternative to emptyDic
// Filling storage with data from service
for result in inputData {
// search for SomeData with required id, add value
// OR create SomeData if there is no such id in array yet
}
OR [personally this appeals to me more]
Store data in [String: [String]] dictionary, where the key is parentID and the associated value is an array of values.
The algorithm of filling this dictionary is pretty the same:
You add new key-value pair for every new parentID
You append new values for parentIDs that are already in the dictionary.
Using the struct approach, you could do something like this (you'll need to adapt it to your code, but that should be straightforward):
struct Categories {
let parentId: String
var values: [String] //notice this needs to be a var, not a let
}
func addItem(categories : inout [Categories], docId: String, name: String) {
if let index = categories.firstIndex(where: { $0.parentId == docId }) {
categories[index].values.append(name)
} else {
categories.append(Categories(parentId: docId, values: [name]))
}
}
func addValues() {
var categories = [Categories]()
addItem(categories: &categories, docId: "4", name: "Test1")
addItem(categories: &categories, docId: "1", name: "Test")
addItem(categories: &categories, docId: "4", name: "Test2")
addItem(categories: &categories, docId: "4", name: "Test3")
print(categories)
//in your code, it'll look more like:
// addItem(categories: &self.newCat, docId: docId, name: result?.name ?? "")
}
Which yields this:
[
StackOverflowPlayground.Categories(parentId: "4", values: ["Test1", "Test2", "Test3"]),
StackOverflowPlayground.Categories(parentId: "1", values: ["Test"])
]
I still wonder whether you maybe just want a Dictionary that is keyed by the parentId, but not knowing your use case, it's hard to say.
This is my Struct,by Swift 3. I know the Dictionary is not stored sequence like an Array and that is my problem. I want to get my Dictionary sequence as I set in ViewArray. I can get the ctC Dictionary, but how can i sort the keys or values as i set in ViewArrayplease and appreciate the help.
struct CTArray {
var ctname: String
var ctkey: String
var ctC: [String:String]
}
var ViewArray:[CTArray] = []
ViewArray += [CTArray(ctname: "kerish", ctkey: "KH", ctC: ["mon":"Apple", "kis":"aone", "Bat":"Best", "orlno":"bOne"])]
ViewArray += [CTArray(ctname: "tainers", ctkey: "TNN", ctC: ["letGor":"one", "washi":"testing", "monk":"lasth"])]
ViewArray += [CTArray(ctname: "techiu", ctkey: "TCU", ctC: ["22":"tt", "wke":"303", "lenth":"highest"])]
i want to show them in my TableView Cell sorted like these:
the ViewArray[0].ctC.key sorted like [mon, kis, Bat, orlno]
the ViewArray[1].ctC.key sorted like [letGor, washi, monk]
the ViewArray[2].ctC.value sorted like [tt, 303, highest]
It is not clear to me what you are asking, but I'll offer this in case it helps.
I know the Dictionary is not stored sequence like an Array and that is my problem.
If you want to access a dictionary by a certain order of its keys then you can create an array of just the keys in the order you required and use that to access the dictionary. An example is probably easier to follow:
Starting with one of your dictionaries:
let dict = ["mon":"Apple", "kis":"aone", "Bat":"Best", "orlno":"bOne"]
print(dict)
this output:
["Bat": "Best", "kis": "aone", "orlno": "bOne", "mon": "Apple"]
which is not what you want. Now introduce a key array and use that to access the dictionary:
let keyOrder = ["mon", "kis", "Bat", "orlno"]
for key in keyOrder
{
print("\(key): \(dict[key]!)")
}
this outputs:
mon: Apple
kis: aone
Bat: Best
orlno: bOne
which is the order you wish.
The same idea can be used anywhere you want to use/show/etc. the keys in a particular order, by using the keyOrder array as part of dictionary access you are making it appear as though the dictionary entries are "stored in sequence" as you put it.
HTH
var object1 = viewArray[0].ctC.flatMap({$0.key})
var object2 = viewArray[1].ctC.flatMap({$0.key})
var object3 = viewArray[2].ctC.flatMap({$0.value})
print(object1)
print(object2)
print(object3)
Outputs:
["Bat", "kis", "orlno", "mon"]
["letGor", "monk", "washi"]
["highest", "tt", "303"]
I have an array of dictionaries [[String : AnyObject]] called rooms in a User object - each dictionary holds a name as the String and an id as the AnyObject.
I want to populate a table view with the names, so I'm trying to loop through the array and grab the String values from the dicts.
if let roomDict = myUser.rooms as? [[String : AnyObject]] {
for (roomNames, _) in roomDict {
cell.textLabel?.text = roomNames
}
}
I'm relatively new and from what I've seen in tutorials and such when looping through dictionaries, you use the underscore to specify that you don't want the second value. So just grab all the first values (in this case, the names), and set them to the roomNames variable.
However I'm confused here because I'm not looping through a dictionary, I'm looping through an array of dictionaries. So I'm not sure how to do that. I did a search and the results I saw generally were asking about JSON, which isn't the case here. How can I do this?
Thanks for any help!
Firstly, your dictionary structure isn't ideal. Rather than having the key as the room name and the value as the identifier, your dictionary should have known key names, with variable values. Keys should not be "data" in a dictionary.
So, rather than
["room1":1]
it would be better if it were
["roomName":"room1", "roomID":1]
with your current structure, however, assuming that there is only one key per dictionary and that is the room name, you can get the names with:
if let rooms = myUser.rooms as? [[String : AnyObject]] {
roomNames = rooms.map({ $0.keys.first!})
}
If you use the better structure I suggested then it would be
if let rooms = myUser.rooms as? [[String : AnyObject]] {
roomNames = rooms.map({ $0["roomName"] as? String ?? ""})
}
I'm not clear about your data structure. If you have an array of dictionaries, and you want all the keys, you could use code like this:
let array = [
["key1": "value1",
"key2": "value2",
"key3": "value3",
"key4": "value4"],
["key5": "value5",
"key6": "value6",
"key7": "value7",
"key8": "value8"],
["key9": "value9",
"key10": "value10",
"key11": "value11",
"key12": "value12"]
]
let keys = array
.map{$0.keys}
.reduce([], +)
print(keys)
That will give you an array of all the keys from all the dictionaries. The keys from each dictionary will be in a jumbled order however, since dictionaries are unordered. You'll get the keys from each inner dictionary in a jumbled order, followed by the keys from the next dictionary in the array, etc.
Sample output:
["key2", "key3", "key4", "key1", "key7", "key8", "key5", "key6", "key9", "key10", "key12", "key11"]
If you want to sort the keys, you can do that:
let keys = array
.map{$0.keys}
.reduce([], +)
.sorted{$0.compare($1, options: .numeric) == .orderedAscending}
(In the above code I'm using the String class's compare(_:options:) function with an options value of .numeric so that "key11" sorts after "key10" instead of ["key1", "key11", "key12", "key2"], which you get from standard string ordering.)
The output of the sorted version (with the .numeric option) is:
["key1", "key2", "key3", "key4", "key5", "key6", "key7", "key8", "key9", "key10", "key11", "key12"]
Without the .numeric option, the output would be:
["key1", "key10", "key11", "key12", "key2", "key3", "key4", "key5", "key6", "key7", "key8", "key9"]
If your keys contain mixed upper/lower case and you want to ignore it, you'd use options of [.numeric, .caseInsensitive] (case insensitive sorting where numbers within strings are compared using numeric value.)
I am trying to add sections to my table view. I need the first section to be an array of strings and the second section to be an array of NSManagedObjects, I use a fetch request to add the data to the array.
I add the section titles to the sections array.
let sections = ["Upcoming", "Checklist Notebooks"]
Then have a dictionary for the data
var sectionItems = [
"Upcoming" : ["1","2", "3", "4"],
"Objects" : [Object]()
]
However when doing the fetch request I get the following error,
Cannot Assign Through Subscript: Subscript is a get-only
Here's my fetch request,
self.sectionItems["Objects"] = delegate.managedObjectContext.executeFetchRequest(request) as! [Object]
How can I create an array/dictionary of two data types to used for the sections ?
Try to add definition for your compound dictionary. You can try this in the playground.
var sectionItems: [String: [Any]] = [
"Upcoming" : ["1","2", "3", "4"],
"Objects" : [AnyObject]()
]
sectionItems["Objects"] = ["123"]
sectionItems["Objects"]
I'm trying to make an app that will select an index at random, something like 0-1000 and then print the key, value, and link of the selected number to three seperate labels on the iPhone simulator.
So from my example, I want to randomly select "0" or "1" and if for instance "1" was chosen; then the key, value, and link information would each be printed to three separate labels on the simulator. The following is what I've been working on in playgrounds. Is there a better way to go about this?
var spDictionary: [String: [String:String]] = [
"0": ["key": "AMZN", "value": "AMAZON", "link": "yahoo"],
"1": ["key": "AAPL", "value": "APPLE", "link": "yahoo2"],
]
And for the random aspect I think it would be something like this but I'm not sure? Sorry for the newbie question.
let randomIndex: Int = Int(arc4random_uniform(UInt32(spDictionary.count)))`
Even for small data structures it's worth it to create a custom class or struct
struct Data {
let key : String
let value : String
let link : String
}
Create an object
let data = Data(key: "AMZN", value: "AMAZON", link: "yahoo")
Get a property
let link = data.link
and you can declare your dictionary
var spDictionary : [String: Data] = ...