I'm confused about how Identifiable arrays work. For instance, I have the following array returned as a response to a function:
Optional (["Jane", "John", "Eric", "Erika", "Motto"])
Now, I want to show this as a list but we know that list items need to conform to Identifiable. How can I conform an array like this to 'Identifiable'? I was looking at this question but it didn't seem to help a lot.
I figured it. simple doing the following should do the job:
#State private var options: [String] = []
// then use this
ForEach(options, id:\.self){ option in
Text(option)
Related
As #vadian suggested, I am learning Xcode from Paul Hudson's 100 days of SwiftUI to better understand the basics (even though I am still struggling with time to deliver working GitHub repository search - no it is not for the job I am working on right now).
I am doing a lesson on Arrays, so pretty basic stuff right now and I struggle to map the String from array on the sorted array. I don't get why, but I get the:
Ambiguous use of 'init'
error.
Here's the code:
let cities = ["London", "Tokyo", "Rome", "Budapest"]
print(cities.sorted())
let citiesSorted = cities.sorted()
let citiesSortedString = citiesSorted.map(String.init).joined(separator:", ")
And it's so really strange, since I pulled the similar thing out before in the same Playground but not with the sorted Array:
var schoolScoresString = schoolScores.map(String.init).joined(separator:", ")
print(schoolScoresString)
And yes I tried changing let to var. It didn't help.
cities is already of type [String], so you're passing a String to String.init, which obviously won't work. If you want to join an array of Strings into a single String, remove the map and just call joined on the array.
let citiesSortedString = citiesSorted.joined(separator:", ")
Hi i'am new to Kotlin and i would like to do an array with named parameter. In Swift i can do :
let analytics = ["organization_login": "toto", "organization_name": "titi", "lead_email": "tata"]
The type is : [String: String]
I Looked all Array and Arraylist in kotlin but i couln't find the equivalent.
What i want it's to be able to give parameter name for my array.
Edit
I misunderstood the swift syntaxe, it's seem that it's only a dictonary, so we just have to use map.
The reason is that [String: String] is not an array, it's a Dictionary.
The equivalent of Dictionary in Kotlin is Map.
Maps can be created like so:
val map = mapOf("string_one" to "string_2", "string_3" to "string_4")
or, if you want to mutate it:
val mutableMap = mutableMapOf("string_one" to "string_2")
You need to use Map as
val map = mapOf("organization_login" to "toto", "organization_name" to "titi")
// immutable map
you can also use sortedMapOf, hashMapOf linkedMapOf etc for different algo based storage.
Note: If you want to add more elements later then make sure to use mutableMapOf
I have an array (Any type) with list of custom object (example object: Vehicle, Parking, Motorbike).
I need to filter this array with a specific type: example Vehicle.
Can you help me?
With compactMap and as?:
let values: [Any] = [1, "string", 0.0, ["array values"]]
let strings = values.compactMap { $0 as? String } // ["string"]
Make sure to do this as soon as possible (as soon as data comes into the system). You should not need [Any] as a class property, for example. If you feel you need that, you probably have mis-designed your data model and actually wanted an enum. Any is not a proper type in Swift; it exists to handle certain edge cases, mostly involving Objective-C, and very special cases like print. If you don't mean "absolutely any type at all is ok here," then you don't mean Any.
For instance, asume
var hierarchicalFileSystem: [[String]] = []
This allows one to support one layer of folders, but there appears to be no way to create an array in Swift like the one above but with an undefined number of nested String arrays.
Am I missing something here?
An array of arrays (of arrays of arrays...) of strings doesn't really make much sense to represent a file system.
What I'd instead recommend is making a class or struct to represent objects in the file system. Perhaps something like this:
struct FileSystemObject {
let name: String
let extension: String?
let isFolder: Bool
let contents: [FileSystemObject]?
}
Something like this let's us represent a file system quite nicely.
let fileSystem = [FileSystemObject]()
So, your fileSystem variable here is an array of FileSystemObjects and it represents the root. Each object within the root has its own set of details (its name, its file extension if it has one, and whether or not its a folder), and if it's a folder it has a non-nil contents property, and if it's a non-empty folder, that contents array of FileSystemObjects contains more file system objects (some of which are folders of course, which contain contents themselves).
What you can perhaps do is create an array with AnyObject and add new depths as you need it
var fileSystem: [AnyObject] = []
This would be a very bad way of representing a file system however and you should really go with some kind of tree structure like
struct Node {
children: [Node]?
parent: Node?
name: String
}
Swift is type-safe language. You have to declare type of your variable, or set it to AnyObject, but please don't. So, answering your question: yes it's possible:
var array: [AnyObject] = [[[1,2,3], [1,2,3]], [[1,2,3],[1,2,3]]]
But this is awful. Try to figure out better representation for your problem. Maybe custom structures.
you can have as much dimensional array as you want. is it a good idea? i don't think ...
var threeDArray: Array<Array<Array<String>>> = []
let oneDArray = ["1","2","3"]
let twoDArray1: Array<Array<String>> = [oneDArray, oneDArray, oneDArray, oneDArray, oneDArray]
let twoDArray2 = twoDArray1 + [["4","5","6"],["7","8","9"]]
threeDArray.append(twoDArray1)
threeDArray.append(twoDArray2)
let arr = [threeDArray,threeDArray,threeDArray]
print(arr.dynamicType) // Array<Array<Array<Array<String>>>>
I am trying to query from parse.com and I would db receiving about 100 objects per time. I used the swift example code on their website, and the app doesn't build with that code. So I looked around and found that people were using code similar to this:
var query = PFQuery(className:"posts")
query.whereKey("post", equalTo: "true")
query.findObjectsInBackgroundWithBlock({ (objects: [AnyObject]?, error: NSError?) -> Void in
// do something
self.myDataArray = objects as! [String]
})
This does not work, because I am trying to convert PFObject to String
I would need to get the one one value from each object into a swift string array [String]. How do I get just the one text value, instead of the PFObject and how do I get it into the swift string array?
I don't speak swift very well, but the problem with the code is it's trying to cast the returned PFObject to a string, but you want to extract a string attribute, so (if you really want to do it):
for object in objects {
var someString = object.valueForKey("someAttributeName") as String
self.myDataArray.addObject(someString)
}
But please make sure you need to do this. I've noticed a lot of new parse/swift users (especially those who are populating tables) have the urge to discard the returned PFObjects in favor of just one of their attributes. Consider keeping the PFObjects and extracting the attributes later as you need them. You might find you'll need other attributes, too.
For starters, I would definitely recommend using the "if let" pattern to qualify your incoming data. This is a nice Swift feature that will help avoid run-time errors.
var query = PFQuery(className:"posts")
query.whereKey("post", equalTo: "true")
query.findObjectsInBackgroundWithBlock(
{ (objects: [AnyObject]?, error: NSError?) -> Void in
// check your incoming data and try to cast to array of "posts" objects.
if let foundPosts = objects as? [posts]
{
// iterate over posts and try to extract the attribute you're after
for post in foundPosts
{
// this won't crash if the value is nil
if let foundString = post.objectForKey("keyForStringYouWant") as? String
{
// found a good data value and was able to cast to string, add it to your array!
self.myDataArray.addObject(foundString)
}
}
})