I currently have a string, that's supposed to be an Array:
var content = "['A','B','C']"
//What I want -> var content = ['A', 'B', 'C']
I need to remove the quotation marks, so that it's just an Array, i.e. String to Array. How would one attempt that?
This looks similar to JSON syntax except that the single quotes should be double quotes.
Well then, let's just do that:
let source = "['A','B','C']"
Replace single quotes with double quotes:
let content = source.stringByReplacingOccurrencesOfString("'", withString: "\"")
Then convert the String to NSData (becomes valid JSON):
guard let data = content.dataUsingEncoding(NSUTF8StringEncoding) else { fatalError() }
Finally, convert the JSON data back to a Swift array of Strings:
guard let arrayOfStrings = try NSJSONSerialization.JSONObjectWithData(data, options: []) as? [String] else { fatalError() }
Result:
print(arrayOfStrings)
["A", "B", "C"]
print(arrayOfStrings[1])
"B"
Here's a semi-hacky solution to your specific example.
let content = "['A','B','C']"
var characters = content.characters
characters.removeFirst(2) // Remove ['
characters.removeLast(2) // Remove ']
let contentArray = String(characters).componentsSeparatedByString("','")
print(contentArray) // ["A", "B", "C"]
Disclaimer/Warning:
This solution isn't robust as it expects your array to only contain objects wrapped in ' characters. It will however work for any length of string (e.g. replacing A with foo will work).
If your actual content string is any more complex than what you have here then I would take Rob's advice and try JSON serialization (especially if this string comes from a place you don't control like the server).
You could do this one:
let arr = content.componentsSeparatedByCharactersInSet(NSCharacterSet (charactersInString: "['],")).filter({!$0.isEmpty})
Explanation:
First, we split the string into an array based upon separators like: [, ', ,, ]
We now have an array with some empty strings, we use filter() to remove them.
And Voila !
Warning:
like #nebs' warning, carefull with this solution. If your string is composed by more complexe strings (ex: "['Hello [buddy]', 'What's up?', 'This is a long text, or not?']"), especially string composed with the separators, you will get an array that will not match with your expected result.
Related
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 trying to create a Base64-String in Swift. I have an example of a Base64-encoded string and its array-counterpart. My problem now is, that I don't know how I get an equivalent array to the one which is given in the example.
Because I didn't want to mess around in my XCode-project I did the following in a playground.
given array:
{"WHERE":{"Class":"%3f","Location":"3b"},"ORDER":["Day ASC","Location DESC"]}
given Base64-string:
eyJXSEVSRSI6eyJDbGFzcyI6IiUzZiIsIkxvY2F0aW9uIjoiM2IifSwiT1JERVIiOlsiRGF5IEFTQyIsIkxvY2F0aW9uIERFU0MiXX0=
First I'm decoding the example-string
let str = "eyJXSEVSRSI6eyJDbGFzcyI6IiUzZiIsIkxvY2F0aW9uIjoiM2IifSwiT1JERVIiOlsiRGF5IEFTQyIsIkxvY2F0aW9uIERFU0MiXX0="
let data = NSData(base64EncodedString: str, options: NSDataBase64DecodingOptions(rawValue: 0))
do {
let result = try NSJSONSerialization.JSONObjectWithData(data!, options: .AllowFragments)
} catch let error {
print(error)
}
//"result" is ["WHERE": ["Class": "%3f", "Location": "3b"], "ORDER": ["Day ASC", "Location DESC"]]
Below I'm trying to reproduce the string from above
var array = [String : AnyObject]()
var arrayPartA = [String : String]()
arrayPartA["Class"] = "%3f"
arrayPartA["Location"] = "3b"
array["ORDER"] = ["Day ASC", "Location DESC"]
array["WHERE"] = arrayPartA
array //The playground says that "array" is ["ORDER": ["Day ASC", "Location DESC"], "WHERE": ["Class": "%3f", "Location": "3b"]]
//"ORDER" and "WHERE" are switched but I don't get them to be at the right position
let utf8str2: NSData = String(array).dataUsingEncoding(NSUTF8StringEncoding)!
let encodedStr = utf8str2.base64EncodedStringWithOptions(NSDataBase64EncodingOptions(rawValue: 0))
//Here "encodedStr" is WyJPUkRFUiI6ICgKICAgICJEYXkgQVNDIiwKICAgICJMb2NhdGlvbiBERVNDIgopLCAiV0hFUkUiOiB7CiAgICBDbGFzcyA9ICIlM2YiOwogICAgTG9jYXRpb24gPSAzYjsKfV0=
//but it should be eyJXSEVSRSI6eyJDbGFzcyI6IiUzZiIsIkxvY2F0aW9uIjoiM2IifSwiT1JERVIiOlsiRGF5IEFTQyIsIkxvY2F0aW9uIERFU0MiXX0=
I would be glad if someone could explain to me what I'm doing wrong and how I can reproduce the given Base64-string.
Since I'm new to this website I apologize in advance for wrong layout or other possible conventions I don't know.
Could you try this please? Is this what you wanted to do? It should convert a Dictionary to base64 String
func jsonToBaseString (yourJSON: [String: String]) -> String? {
do {
let jsonData = try JSONSerialization.data(withJSONObject: yourJSON, options: JSONSerialization.WritingOptions.prettyPrinted)
return
jsonData.base64EncodedString(options: .endLineWithCarriageReturn)
} catch {
return nil
}
}
Dictionary is Swifts JSON representation...
Two important things to understand:
What you are calling an array is not an array, it's a JSON dictionary (containing an array for the ORDER key).
Be careful not to confuse the syntax of arrays and dictionaries between Swift and JSON.
In Swift, an array: [0, 1], a dictionary: ["a":0, "b":1].
In JSON, an array: [0, 1], a dictionary: {"a":0, "b":1}.
A Swift dictionary is an unordered collection. There's no "position" for key-value pairs.
You'll need to change several things:
Your input string (not serialized) is not an array, but a JSON object.
Try constructing your string with a proper JSON library, such as SwiftyJSON.
String(array) is not enough to consistently convert your objects to strings. You should use a JSON serializer (such as SwiftyJSON json.rawString()).
let follow recommendation to use some json serialization, but take in account that
{
"alfa": 1,
"beta": true
}
and
{"beta":true,"alfa":1}
represents in JSON notation the same object even though their string representation ( doesn't matter if base64 encoded or not ) are different.
I am trying to create a array to hold dictionaries.
var deaultScoreResults : [Dictionary<String, Int>] = [];
But when I try to add a dictionary key:value pair I get:
deaultScoreResults.append(["Study Up!", 1]);
Error;
Type 'Dictionary' does not conform to protocol
'ArrayLiteralConvertible'
Square brackets surrounding a comma separated list of values is an array literal.
["this", "is", "a", "swift", "literal", "array"]
For a literal dictionary, you need a comma separated list of key:value pairs:
[1:"this", 2:"is", 3:"a", 4:"swift", 5:"literal", 6:"dictionary"]
To fix the error, you simply need to change your comma to a colon:
defaultScoreResults.append(["Study Up!":1])
However, based on your previous question, I'm going to assume an array of <String, Int> dictionaries isn't anywhere near what you're looking for.
I would suggest that you want simply an <Int, String> dictionary:
var defaultScoreResults = Dictionary<Int, String>()
defaultScoreResults[1] = "Study Up!"
Try this:
var deaultScoreResults = [Dictionary<String, Int>]()
deaultScoreResults.append(["Study Up!":1])
You could also declare it like this:
var deaultScoreResults = [[String:Int]]()
I want to compare two arrays with each other and append the value that is not in the other array to a new array. The problem now is that all of the values that does not equal the other array already get appended, but I want only the values that are new in the other array getting appended.
I hope that the problem is clear. Sorry if it's a very vague question. I try to be clear haha.
The code and output is printed below:
// Iterate through all possible values
for i in 0...messages.count-1{
var match = false
for r in 0...self.messages.count-1{
println("NIEUWE" + messages[i].getID() + "OUDE" + self.messages[r].getID())
if(messages[i].getID().toInt() == self.messages[r].getID().toInt()){
var match = true
println(match)
break
}
}
if (!match) {
newArray.append(messages[i])
println(newArray)
}
}
Output:
NIEUWE170OUDE170
NIEUWE170OUDE171
true
[PostDuif.Message]
NIEUWE171OUDE170
true
[PostDuif.Message, PostDuif.Message]
NIEUWE172OUDE170
true
This "I want to compare two arrays with each other and append the value that is not in the other array to a new array" is just 'set difference'
var s1 = Set(["a", "b", "c"]) // this to be similar to your need
var s2 = Set(["b", "c", "d"])
var s3 = s2.subtract (s1)
As such:
9> var s3 = s2.subtract(s1)
s3: Set<String> = {
[0] = "d"
}
Note that you have subtract, intersect, and union with inPlace options as methods on the Set type. New to Swift 1.2.
For my project, I extracted tweets from a CSV file in Swift. Problem is now all tweets are parsed as one element in an array, separated by ",".
let tweetsOfColumns = columns["tweet"]
let seperatedColumns = tweetsOfColumns.componentsSeparatedByString(",")
Error message: '[String]?' does not have a member named
'componentsSeparatedByString'.
I checked if tweetsOfColumns contains multiple elements, but it doesn't allow me to subscript with tweetsOfColumns[index].
Looking at the link you reference, columns["tweets"] is going to give you back an array of the values from the "tweets" column, so it's what you need already, there's no additional comma's to split things on, you just need:
let seperatedColumns = columns["tweet"]
to have an array containing the tweet column for each row.
When you try to get an element from a dictionary, like
columns["tweet"]
it will give you back an optional, because if there is nothing associated with the key, it gives you back nil (None), otherwise the value wrapped in an optional (Some(data)).
So you have to unwrap the optional for example:
columns["tweet"]!
You have to either use the optional ? to access the string:
let seperatedColumns = tweetsOfColumns?.componentsSeparatedByString(",")
But you should unwrap it:
if let unwrappedTweets = tweetsOfColumns?.componentsSeparatedByString(","){
let seperatedColumns = unwrappedTweets
}
The problem is probably that you'll get an optional back, which you have to unwrap. And the easiest and most elegant is to use the if-let unwrapper.
if let tweetsOfColumns = columns["tweet"] {
let seperatedColumns = tweetsOfColumns.componentsSeparatedByString(",")
// do something with the seperatedColumns
}
Based on David's question and the OP's response in the OP comments, you can use map on the Array returned by columns["tweet"]. Please post actual data/code in the future.
let columns = [
"tweet":["handleX,tag1,tag2,textA,textB",
"handleY,tag1,tag2,textC,textD"]]
var chunk = [[String]]()
if columns["tweet"] != nil {
chunk = columns["tweet"]!.map {
return $0.componentsSeparatedByString(",")
}
}