I'm developing an iOS app and I want to access a specific value in a Dictionary using Array().
My dictionary contains an array, which contains structs.
let array = [(key: "S", value: [Thunderbolt.repoStruct(repoName: "Semiak Repo", repoURL: "https://repo.semiak.dev", icon: Optional("iconRound"))]), (key: "T", value: [Thunderbolt.repoStruct(repoName: "Thunderbolt iOS Utilities", repoURL: "https://repo.thunderbolt.semiak.dev", icon: Optional("iconRound"))])]
I'm making an UITableView with the array: the section name is the key value, the cell title is the repoStruct.repoName value, and the same with the following values.
To access repoName I'd use Array(array)[0].1[0].repoName.
The problem is that I do not know the exact location I want to access, instead, I use indexPath to know which value I need:
Array(array)[indexPath.section].indexPath.row[0].repoName
This should return me the repoName of the cell, but instead gives me the following error: Value of tuple type '(key: String, value: [repoStruct])' has no member 'indexPath'
I also tried using:
let row = indexPath.row
Array(array)[indexPath.section].row[0].repoName
but it gives me the same error: Value of tuple type '(key: String, value: [repoStruct])' has no member 'row'
I do not know why Array(array)[0].1 works and returns me the value, but Array(array)[indexPath.section].row doesn't. It is doing the same: accessing a value using the position, which is an int, such as indexPath.
How could I accomplish this?
Thanks in advance.
You are strongly discouraged from using tuples in a data source array. Replace the tuple with an extra struct
struct Section {
let name : String
let items : [Thunderbolt.repoStruct]
}
let array = [Section(name: "S", items: [Thunderbolt.repoStruct(repoName: "Semiak Repo", repoURL: "https://repo.semiak.dev", icon: Optional("iconRound"))],
Section(name: "T", items: [Thunderbolt.repoStruct(repoName: "Thunderbolt iOS Utilities", repoURL: "https://repo.thunderbolt.semiak.dev", icon: Optional("iconRound"))]]
and get an item at index path
let section = array[indexPath.section]
let item = section.items[indexPath.row]
let name = item.repoName
First of all, your array is already an array, so there's no need to say Array(array) - simply array will suffice, although generic names like this should be avoided.
I do not know why array[0].1[0] works
Let's pick this apart - your're accessing the first element in array via [0] and within that, the second element of the tuple .1, and lastly the first element of that valuearray. You could use array[0].value[0] for the same effect and make the code more readable.
but array[indexPath.section].row doesn't
That's because your array does not contain anything called row.
Use array[indexPath.section].value[indexPath.row].repoName instead.
Please try this code.
let dictData = arr[indexpath.section] //Element of section
let value = dictData["value"] //Value added in value in The element
let name = value[indexpath.row].reponame //Gives you name
Related
I'm trying to filter a set of objects based on values in one of their elements based on another array. I've got it working with filter just fine if the search is "OR" - it returns give me all objects for which at least one of the strings in the search array is found.
But I can't figure out how to make it work as an AND search - returning only the objects that match ALL of the strings in the search array.
Example:
struct Schedule {
let title: String
let classTypes: [String]
}
let schedule1 = Schedule(title: "One", classTypes: ["math","english","chemistry","drama"])
let schedule2 = Schedule(title: "Two", classTypes: ["pe","math","biology"])
let schedule3 = Schedule(title: "Three", classTypes: ["english","history","math","art"])
let schedules = [schedule1, schedule2, schedule3]
let searchArray = ["math", "english"]
//works for OR - "math" or "english"
var filteredSchedules = schedules.filter { $0.classTypes.contains(where: { searchArray.contains($0) }) }
I'd like to find a way for it to use the same search array
let searchArray = ["math", "english"]
But only return items 1 & 3 - as they both have BOTH math and english in the list.
There are good examples of AND conditions when the AND is across different search criteria: car type and colour - but I've been unable to find an example where the criteria are dynamically based on items in an array. For context, I could have dozens of schedules with 20+ class types.
You can work with a Set, isSubset will return true if the schedules element contains all elements of the searchSet
let searchSet = Set(searchArray)
var filteredSchedules = schedules.filter { searchSet.isSubset(of: $0.classTypes) }
As suggested by #LeoDabus it might be worth changing the type of classTypes to Set instead of arrays (if order doesn't matter) since they seems to be unique and then the filtering can be done in the opposite way without the need to convert searchArray each time
var filteredSchedules = schedules.filter { $0.classTypes.isSuperset(of: searchArray) }
The problem with the ECMA standard for sort of Object.keys() is known:
Object.keys() handle all keys with integer (example: 168), including integer as strings (example: "168"), as a integer. The result is, both are the same (168 === "168"), and overwrite itself.
var object = {};
object["168"] = 'x';
object[168] = 'y';
Object.keys(object); // Array [ "168" ]
object[Object.keys(object)]; // "y"
Interestingly, all keys (including pure integer keys) are returned as a string.
The ecma262 wrote about this: All keys will be handle as a integer, expect the key is a String but is not an array index.
https://tc39.es/ecma262/#sec-ordinaryownpropertykeys
That should tell us: 168 === "168". A toString() do not solve the problem.
var object = {};
object[[3].toString()] = 'z';
object[[1].toString()] = 'x';
object[[2].toString()] = 'y';
Object.keys(object);
// Array(3) [ "1", "2", "3" ]
Paradoxically, in this case, only integer apply as "enumerable" (it's ignoring array.sort(), that sort also strings with letters.).
My question about this is simple: How can i prevent the sort function in Object.keys()? I have testet the Object.defineProperties(object, 1, {value: "a", enumerable: true/false}), but that mean not realy enumerable in the case of integer or string or integer-like string. It means only should it be counted with or not. It means "counted" like omit (if it false), not "enumerabled" like ascending or descending.
A answere like that is not a good answer: Please use only letters [a-zA-Z] or leastwise a letter at the first position of keyword.
What I want: That the keys are not sorted, but output in the order in which they were entered, whether integer, string or symbol.
Disclaimer: Please solutions only in JavaScript.
Javascript Objects are unordered by their nature. If you need an ordered object-like variable I would suggest using a map.
To achieve what you're looking for with a map instead of object you'd do something like the below:
var map1 = new Map();
map1.set("123", "c");
map1.set(123, "b");
var iterator1 = map1.keys();
var myarray = [];
for (var i = 0; i < map1.size; i++) {
myarray.push(iterator1.next().value);
}
console.log(myarray);
// Array ["123", 123]
Unfortunately it's not compatible with IE and I'm not sure how else you could achieve what you need without it. A quick Google did return something about jQuery maps, though.
If you don't want to use jQuery and still need to support IE some points are below:
Is there anything stopping you using an array rather than JS object to store the data you need? This will retain the order per your requirements unlike objects. You could have an object entry in each iteration which represents the key then use a traditional foreach to obtain them as an array. I.e.
The array:
var test_array = [
{key: 123, value: 'a value here'},
{key: "123", value: 'another value here'}
];
// console.log(test_array);
Getting the keys:
var test_array_keys = [];
test_array.forEach(function(obj) { test_array_keys.push(obj['key']); } );
// console.log(test_array_keys);
Then if you needed to check whether the key exists before adding a new entry (to prevent duplicates) you could do:
function key_exists(key, array)
{
return array.indexOf(key) !== -1;
}
if(key_exists('12345', test_array_keys))
{
// won't get here, this is just for example
console.log('Key 12345 exists in array');
}
else if(key_exists('123', test_array_keys))
{
console.log('Key 123 exists in array');
}
Would that work? If not then the only other suggestion would be keeping a separate array alongside the object which tracks the keys and is updated when an entry is added or removed to/from the object.
Object Keys sorted and store in array
First Creating student Object. then sort by key in object,last keys to store in array
const student={tamil:100, english:55, sci:85,soc:57}
const sortobj =Object.fromEntries(Object.entries(student).sort())
console.log(Object.keys(sortobj))
use map instead of an object.
let map = new Map()
map.set("a", 5)
map.set("d", 6)
map.set("b", 12)
to sort the keys (for example, to update a chart data)
let newMap = new Map([...map.entries()].sort())
let keys = Array.from(newMap.keys()) // ['a','b','d']
let values = Array.from(newMap.values()) // [5,12,6]
I'm brand new to Go and having some trouble with nested data structures. Below is a array of hashes I mocked up that I need to make in Golang. I'm just confused with the whole having to declare the variable type beforehand and whatnot. Any ideas?
var Array = [
{name: 'Tom', dates: [20170522, 20170622], images: {profile: 'assets/tom-profile', full: 'assets/tom-full'}},
{name: 'Pat', dates: [20170515, 20170520], images: {profile: 'assets/pat-profile', full: 'assets/pat-full'}}
...,
... ]
What is called a 'hash' in Ruby is called a 'map' (translating keys to values) in Go.
However, Go is a statically typechecked language. A map can only map a certain type to another type, e.g. a map[string]int maps string values to integeger. That is not what you want here.
So what you want is a struct. Indeed, you need to define the type beforehand. So what you would do:
// declaring a separate 'Date' type that you may or may not want to encode as int.
type Date int
type User struct {
Name string
Dates []Date
Images map[string]string
}
Now that this type is defined, you can use it in another type:
ar := []User{
User{
Name: "Tom",
Dates: []Date{20170522, 20170622},
Images: map[string]string{"profile":"assets/tom-profile", "full": "assets/tom-full"},
},
User{
Name: "Pat",
Dates: []Date{20170515, 20170520},
Images: map[string]string{"profile":"assets/pat-profile", "full": "assets/pat-full"},
},
}
Note how we are defining User as a struct, but images as a map of string to image. You could also define a separate Image type:
type Image struct {
Type string // e.g. "profile"
Path string // e.g. "assets/tom-profile"
}
You would then not define Images as map[string]string but as []Image, that is, slice of Image structs. Which one is more appropriate depends on the use case.
You don't need to declare the variable type beforehand, at least not in this simple example, although you need to "mention" your types when initializing your values with composite literals.
For example this [{}] (array of objects?) makes no sense to the Go compiler, instead you need to write something like this []map[string]interface{}{} (slice of maps whose keys are strings and whose values can have any type)
To break it down:
[] - slice of whatever type comes after it
map - builtin map (think hash)
[string] - inside the square brackets is the type of the map key,
can be almost any type
interface{} - the type of the map values
{} - this initializes/allocate the whole thing
So your example in Go would look something like this:
var Array = []map[string]interface{}{
{"name":"Tom", "dates": []int{20170522, 20170622}, "images": map[string]string{"profile": "assets/tom-profile", "full": "assets/tom-full"}},
{"name":"Pat", "dates": []int{20170515, 20170520}, "images": map[string]string{"profile": "assets/pat-profile", "full": "assets/pat-full"}},
// ...
}
Read more on maps and what key types you can use here: https://golang.org/ref/spec#Map_types
That said, in Go, most of the time, you would first define your structured types more concretely and then use them instead of maps, so something like this makes more sense in Go:
type User struct {
Name string
Dates []int
Images Images
}
type Images struct {
Profile string
Full string
}
var Array = []User{
{Name:"Tom", Dates:[]int{20170522, 20170622}, Images:Images{Profile:"assets/tom-profile", Full:"assets/tom-full"}},
{Name:"Pat", Dates:[]int{20170515, 20170520}, Images:Images{Profile:"assets/pat-profile", Full:"assets/pat-full"}},
}
I have a dictionary containing UIColor objects hashed by an enum value, ColorScheme:
var colorsForColorScheme: [ColorScheme : UIColor] = ...
I would like to be able to extract an array of all the colors (the values) contained by this dictionary. I thought I could use the values property, as is used when iterating over dictionary values (for value in dictionary.values {...}), but this returns an error:
let colors: [UIColor] = colorsForColorSchemes.values
~~~~~~~~~~~~~~~~~~~~~^~~~~~~
'LazyBidrectionalCollection<MapCollectionView<Dictionary<ColorScheme, UIColor>, UIColor>>' is not convertible to 'UIColor'
It seems that rather than returning an Array of values, the values method returns a more abstract collection type. Is there a way to get an Array containing the dictionary's values without extracting them in a for-in loop?
As of Swift 2.0, Dictionary’s values property now returns a LazyMapCollection instead of a LazyBidirectionalCollection. The Array type knows how to initialise itself using this abstract collection type:
let colors = Array(colorsForColorSchemes.values)
Swift's type inference already knows that these values are UIColor objects, so no type casting is required, which is nice!
You can map dictionary to an array of values:
let colors = colorsForColorScheme.map { $0.1 }
Closure takes a key-value tuple from dictionary and returns just a value. So, map function produces an array of values.
More readable version of the same code:
let colors = colorsForColorScheme.map { (scheme, color) in
return color
}
UPDATE
From Xcode 9.0, dictionary values can be accessed using values property, which conforms to Collection protocol:
let colors = colorsForColorScheme.values
Typically you just want it as an array:
let colors = Array(dict.values)
and that's it.
Use colorsForColorScheme.map({$0.value})
you can create an extension on LazyMapCollection
public extension LazyMapCollection {
func toArray() -> [Element]{
return Array(self)
}
}
colorsForColorSchemes.values.toArray() or colorsForColorSchemes.keys.toArray()
Firstly, from the following statement, it seems that your variable(dictionary) name is colorsForColorScheme
var colorsForColorScheme: [ColorScheme : UIColor] = ...
while you are trying to get the values from colorsForColorSchemes dictionary when you did-
let colors: [UIColor] = colorsForColorSchemes.values
which should give you a compile time error. Anyways I am assuming that you had a typo, and you dictionary's name is colorsForColorSchemes. So, here is the solution-
As mentioned earlier, because of the type inference property in swift, your code can infer that the returned type from the .values function is returning an array of UIColor. However, Swift wants to be type-safe, so when you store the values in the colors array, you need to explicitly define that. For swift 5 and above, now you could just do following-
let colors = [UIColor](colorsForColorSchemes.values)
You can also use flatMap:
let colors = colorsForColorScheme.values.flatMap { $0 }
I've found this to be the most useful in Swift 5:
colorsForColorSchemes.allValues
See docs - https://developer.apple.com/documentation/foundation/nsdictionary/1408915-allvalues
I’m new to Swift and have been having some troubles figuring out some aspects of Arrays and Dictionaries.
I have an array of dictionaries, for which I have used Type Aliases - e.g.
typealias myDicts = Dictionary<String, Double>
var myArray : [myDicts] = [
["id":0,
"lat”:55.555555,
"lng”:-55.555555,
"distance":0],
["id":1,
"lat": 44.444444,
"lng”:-44.444444,
"distance":0]
]
I then want to iterate through the dictionaries in the array and change the “distance” key value. I did it like this:
for dict:myDicts in myArray {
dict["distance"] = 5
}
Or even specifically making sure 5 is a double with many different approaches including e.g.
for dict:myDicts in myArray {
let numberFive : Double = 5
dict["distance"] = numberFive
}
All my attempts cause an error:
#lvalue $T5' is not identical to '(String, Double)
It seems to be acting as if the Dictionaries inside were immutable “let” rather than “var”. So I randomly tried this:
for (var dict:myDicts) in myArray {
dict["distance"] = 5
}
This removes the error and the key is indeed assigned 5 within the for loop, but this doesn't seem to actually modify the array itself in the long run. What am I doing wrong?
The implicitly declared variable in a for-in loop in Swift is constant by default (let), that's why you can't modify it directly in the loop.
The for-in documentation has this:
for index in 1...5 {
println("\(index) times 5 is \(index * 5)")
}
In the example above, index is a constant whose value is automatically
set at the start of each iteration of the loop. As such, it does not
have to be declared before it is used. It is implicitly declared
simply by its inclusion in the loop declaration, without the need for
a let declaration keyword.
As you've discovered, you can make it a variable by explicitly declaring it with var. However, in this case, you're trying to modify a dictionary which is a struct and, therefore, a value type and it is copied on assignment. When you do dict["distance"] = 5 you're actually modifying a copy of the dictionary and not the original stored in the array.
You can still modify the dictionary in the array, you just have to do it directly by looping over the array by index:
for index in 0..<myArray.count {
myArray[index]["distance"] = 5
}
This way, you're sure to by modifying the original dictionary instead of a copy of it.
That being said, #matt's suggestion to use a custom class is usually the best route to take.
You're not doing anything wrong. That's how Swift works. You have two options:
Use NSMutableDictionary rather than a Swift dictionary.
Use a custom class instead of a dictionary. In a way this is a better solution anyway because it's what you should have been doing all along in a situation where all the dictionaries have the same structure.
The "custom class" I'm talking about would be a mere "value class", a bundle of properties. This was kind of a pain to make in Objective-C, but in Swift it's trivial, so I now do this a lot. The thing is that you can stick the class definition for your custom class anywhere; it doesn't need a file of its own, and of course in Swift you don't have the interface/implementation foo to grapple with, let alone memory management and other stuff. So this is just a few lines of code that you can stick right in with the code you've already got.
Here's an example from my own code:
class Model {
var task : NSURLSessionTask!
var im : UIImage!
var text : String!
var picurl : String!
}
We then have an array of Model and away we go.
So, in your example:
class MyDict : NSObject {
var id = 0.0
var lat = 0.0
var lng = 0.0
var distance = 0.0
}
var myArray = [MyDict]()
let d1 = MyDict()
d1.id = 0
d1.lat = 55.55
d1.lng = -55.55
d1.distance = 0
let d2 = MyDict()
d2.id = 0
d2.lat = 44.44
d2.lng = -44.44
d2.distance = 0
myArray = [d1,d2]
// now we come to the actual heart of the matter
for d in myArray {
d.distance = 5
}
println(myArray[0].distance) // it worked
println(myArray[1].distance) // it worked
Yes, the dictionary retrieved in the loop is immutable, hence you cannot change.
I'm afraid your last attempt just creates a mutable copy of it.
One possible workaround is to use NSMutableDictionary:
typealias myDicts = NSMutableDictionary
Have a class wrapper for the Swift dictionary or array.
class MyDictionary: NSObject {
var data : Dictionary<String,Any>!
init(_ data: Dictionary<String,Any>) {
self.data = data
}}
MyDictionary.data