Hi I'm very new to Swift and I'm trying to make a simple application.
The app gets data from server as JSON format.
func addLangList(completion: #escaping ([String], [String]) -> Void) {
let request = NetworkRequest()
let reqUrl = NetworkInformation.serverAddr + "/word/purpose"
let parameters: Parameters = ["category": "lang"]
request.sendGetRequest(url: reqUrl, parameters: parameters, success: { (response) in
let json = JSON(response)
let isSuccess = json[ServerResponseKey.KEY_RESULT]
if isSuccess == true {
var resultMessage:JSON = json[ServerResponseKey.KEY_MESSAGE]
let lang = resultMessage["lang"].arrayValue
let purpose = resultMessage["purpose"].arrayValue
completion(lang, purpose)
}
}, fail: request.CommonNetworkFailureHandler)
}
By using Swiftyjson, the function converts the data received into JSON format. Inside the closure, 'completion' is called for further process in caller. An error occurs at 'completion(lang, purpose). Xcode says
" Cannot convert value of type '[JSON]' to expected argument type '[String]'".
The error, I guess, because .arrayValue doesn't change resultMessage["lang"] into [String] type....Can anyone give me some advice??
Those 2 arrays
let lang = resultMessage["lang"].array
let purpose = resultMessage["purpose"].array
are of type JSON which isn't String , you need to cast them
let langStr = lang.map { $0.string }
let purposeStr = purpose.map { $0.string }
let langStr = lang.map { $0.string }
let purposeStr = purpose.map { $0.string }
Related
I have received this response from the server and I am sure there must be a more efficient way to convert it into an object.
I have the following response:
[
id=2997,rapidViewId=62,state=ACTIVE,name=Sprint7,startDate=2018-11-20T10:28:37.256Z,endDate=2018-11-30T10:28:00.000Z,completeDate=<null>,sequence=2992,goal=none
]
How do I convert it nicely into a well formed swift object in the simplest way?
Here is my attempt which gives me just the Sprint Value
if sprintJiraCustomField.count > 0 {
let stringOutput = sprintJiraCustomField.first?.stringValue // convert output to String
let name = stringOutput?.components(separatedBy: "name=") // get name section from string
let nameFieldRaw = name![1].components(separatedBy: ",") // split out to the comma
let nameValue = nameFieldRaw.first!
sprintDetail = nameValue// show name field
}
Not sure what format you want but the below code will produce an array of tuples (key, value) but all values are strings so I guess another conversion is needed afterwards
let items = stringOutput.components(separatedBy: ",").compactMap( {pair -> (String, String) in
let keyValue = pair.components(separatedBy: "=")
return (keyValue[0], keyValue[1])
})
This is a work for reduce:
let keyValueStrings = yourString.components(separatedBy: ",")
let dictionary = keyValueStrings.reduce([String: String]()) {
(var aggregate: [String: String], element: String) -> [String: String] in
let elements = element.componentsSeparatedByString("=")
let key = elements[0]
// replace nil with the value you want to use if there is no value
let value = (elements.count > 1) ? elements[1] : nil
aggregate[key] = value
return aggregate
}
This is a functional approach, but you can achieve the same using a for iteration.
So then you can use Swift’s basic way of mapping. for example you will have your custom object struct. First, you will add an init method to it. Then map your object like this:
init(with dictionary: [String: Any]?) {
guard let dictionary = dictionary else { return }
attribute = dictionary["attrName"] as? String
}
let customObjec = CustomStruct(dictionary: dictionary)
We already have some suggestion to first split the string at each comma and then split each part at the equals sign. This is rather easy to code and works well, but it is not very efficient as every character has to be checked multiple times. Writing a proper parser using Scanner is just as easy, but will run faster.
Basically the scanner can check if a given string is at the current position or give you the substring up to the next occurrence of a separator.
With that the algorithm would have the following steps:
Create scanner with the input string
Check for the opening bracket, otherwise fail
Scan up to the first =. This is the key
Consume the =
Scan up to the first , or ]. This is the value
Store the key/value pair
If there is a , consume it and continue with step 3
Consume the final ].
Sadly the Scanner API is not very Swift-friendly. With a small extension it is much easier to use:
extension Scanner {
func scanString(_ string: String) -> Bool {
return scanString(string, into: nil)
}
func scanUpTo(_ delimiter: String) -> String? {
var result: NSString? = nil
guard scanUpTo(delimiter, into: &result) else { return nil }
return result as String?
}
func scanUpTo(_ characters: CharacterSet) -> String? {
var result: NSString? = nil
guard scanUpToCharacters(from: characters, into: &result) else { return nil }
return result as String?
}
}
With this we can write the parse function like this:
func parse(_ list: String) -> [String: String]? {
let scanner = Scanner(string: list)
guard scanner.scanString("[") else { return nil }
var result: [String: String] = [:]
let endOfPair: CharacterSet = [",", "]"]
repeat {
guard
let key = scanner.scanUpTo("="),
scanner.scanString("="),
let value = scanner.scanUpTo(endOfPair)
else {
return nil
}
result[key] = value
} while scanner.scanString(",")
guard scanner.scanString("]") else { return nil }
return result
}
I am trying to append 2 arrays and I get the following error message.
Cannot convert value of type '[[String.SubSequence]]' (aka 'Array>') to expected argument type '[String]'
This is my code.
func getFiles() {
print("Enter getFiles")
arrayBookName.removeAll()
let fileManager = FileManager.default
let path = Bundle.main.path(forResource: "LVAudioBooks", ofType: nil)
do {
let items = try fileManager.contentsOfDirectory(atPath: path!)
for item in items {
var arrayTemp = [item.split(separator: ".")]
//arrayBookName += [["temp", "help"]]
arrayBookName.append(arrayTemp) <-- error occurs here**
//print(arrayBookName, arrayTemp)
}
} catch {
// failed to read directory – bad permissions, perhaps?
}
print(arrayBookName.count)
print(arrayBookName)
print("Leave getFiles")
}
String.split(separator:) returns the type [Substring] and not [String].
To convert [Substring] to [String], in your case, you can use the following:
var arrayTemp = [item.split(separator: ".").map({ String($0) })]
Here is a one liner:
items.forEach{arrayBookName.append(contentsOf: $0.split(separator: ".").map{String($0)})}
instead of :
for item in items {
var arrayTemp = [item.split(separator: ".")]
//arrayBookName += [["temp", "help"]]
arrayBookName.append(arrayTemp) <-- error occurs here**
//print(arrayBookName, arrayTemp)
}
I am consuming an API that gives me the next page in the Header inside a field called Link. (For example Github does the same, so it isn't weird.Github Doc)
The service that I am consuming retrieve me the pagination data in the following way:
As we can see in the "Link" gives me the next page,
With $0.response?.allHeaderFields["Link"]: I get </api/games?page=1&size=20>; rel="next",</api/games?page=25&size=20>; rel="last",</api/games?page=0&size=20>; rel="first".
I have found the following code to read the page, but it is very dirty... And I would like if anyone has dealt with the same problem or if there is a standard way of face with it. (I have also searched if alamofire supports any kind of feature for this but I haven't found it)
// MARK: - Pagination
private func getNextPageFromHeaders(response: NSHTTPURLResponse?) -> String? {
if let linkHeader = response?.allHeaderFields["Link"] as? String {
/* looks like:
<https://api.github.com/user/20267/gists?page=2>; rel="next", <https://api.github.com/user/20267/gists?page=6>; rel="last"
*/
// so split on "," the on ";"
let components = linkHeader.characters.split {$0 == ","}.map { String($0) }
// now we have 2 lines like '<https://api.github.com/user/20267/gists?page=2>; rel="next"'
// So let's get the URL out of there:
for item in components {
// see if it's "next"
let rangeOfNext = item.rangeOfString("rel=\"next\"", options: [])
if rangeOfNext != nil {
let rangeOfPaddedURL = item.rangeOfString("<(.*)>;", options: .RegularExpressionSearch)
if let range = rangeOfPaddedURL {
let nextURL = item.substringWithRange(range)
// strip off the < and >;
let startIndex = nextURL.startIndex.advancedBy(1) //advance as much as you like
let endIndex = nextURL.endIndex.advancedBy(-2)
let urlRange = startIndex..<endIndex
return nextURL.substringWithRange(urlRange)
}
}
}
}
return nil
}
I think that the forEach() could have a better solution, but here is what I got:
let linkHeader = "</api/games?page=1&size=20>; rel=\"next\",</api/games?page=25&size=20>; rel=\"last\",</api/games?page=0&size=20>; rel=\"first\""
let links = linkHeader.components(separatedBy: ",")
var dictionary: [String: String] = [:]
links.forEach({
let components = $0.components(separatedBy:"; ")
let cleanPath = components[0].trimmingCharacters(in: CharacterSet(charactersIn: "<>"))
dictionary[components[1]] = cleanPath
})
if let nextPagePath = dictionary["rel=\"next\""] {
print("nextPagePath: \(nextPagePath)")
}
//Bonus
if let lastPagePath = dictionary["rel=\"last\""] {
print("lastPagePath: \(lastPagePath)")
}
if let firstPagePath = dictionary["rel=\"first\""] {
print("firstPagePath: \(firstPagePath)")
}
Console output:
$> nextPagePath: /api/games?page=1&size=20
$> lastPagePath: /api/games?page=25&size=20
$> firstPagePath: /api/games?page=0&size=20
I used components(separatedBy:) instead of split() to avoid the String() conversion at the end.
I created a Dictionary for the values to hold and removed the < and > with a trim.
This is my JSON data, how can I get src data in 0 in pickArray?
"pickArray" : "{\"0\":{\"src\":\"https:\/\/fb-s-d-a.akamaihd.net\/h-ak-xpl1\/v\/t1.0-9\/p720x720\/18010403_1525007564199498_8009700960533638318_n.png?oh=25dbc9c1522dcfdd1d15cdd3e8c0c7da&oe=59997685&__gda__=1502470695_f212ade003e9b1c4ddc6a3ab6cc9e7e7\",\"width\":720,\"height\":720}}"
If I do it like this:
let dataArray = json["pickArray"]
print("dataArray = ",dataArray)
dataArray = {"0":{"src":"https://fb-s-d-a.akamaihd.net/h-ak-xpl1/v/t1.0-9/p720x720/18010403_1525007564199498_8009700960533638318_n.png?oh=25dbc9c1522dcfdd1d15cdd3e8c0c7da&oe=59997685&__gda__=1502470695_f212ade003e9b1c4ddc6a3ab6cc9e7e7","width":720,"height":720}}
But if I do it like this, show null:
let srcArray = dataArray["0"]
print("srcArray = ",srcArray)
I'm using swift3.0
Its looks like that with key pickArray you are having JSON response in String so get that string and convert it data and get JSON from it and then get src from it.
let stringResponse = json["pickArray"].stringValue
if let data = stringResponse.data(using: .utf8) {
let pickArray = JSON(data: data)
//Now access the pickArray to get the src
var sortedKeys = [String]()
if let allKeys = pickArray.dictionaryObject {
sortedKeys = Array(allKeys.keys).sorted { $0.compare($1, options: .numeric) == .orderedAscending }
}
for key in sortedKeys {
print(pickArray[key]["src"].stringValue)
print(pickArray[key]["width"].intValue)
print(pickArray[key]["height"].intValue)
}
}
let srcArray = dataArray["0"].dictionaryObject!
print("srcArray = \(srcArray)")
Now you can access element of "0" value as like below. Hope this work for you.
let jsonScr = JSON(srcArray)
let srcURL = jsonScr["scr"].stringValue
I'm attempting to use string concatenation to create a URL for a network call. However, I'm getting intermittent results when trying to concatenate strings.
Attached image shows it concatenates to just "h". Relevant code added below.
Am I missing something?
Thank you.
/* Constants */
private let baseURL = "https://someurl.com/"
private let URLSuffix = "anotherString"
private let typeItem = "item/"
class HITNetworkCoordinator: NSObject {
class var sharedInstance : HITNetworkCoordinator {
return _HITNetworkCoordinatorInstance
}
func downloadItem (itemID: Int) {
let taskURLString = baseURL + typeItem + String(itemID) + URLSuffix
let taskURL = NSURL.URLWithString(taskURLString)
let task = NSURLSession.sharedSession().dataTaskWithURL(taskURL, completionHandler: { (data, response, error) -> Void in
var responseDict : NSDictionary? = NSJSONSerialization.JSONObjectWithData(data, options: nil, error: nil) as? NSDictionary
println(responseDict)
})
task.resume()
}
Try this - let taskURLString = "(baseURL) (typeItem) + String(itemID) + (URLSuffix) " and see what happens
String concatenation seems to get flakier as you increase the number of concat operators (+) in an expression. I gave up a while ago, and started using evaluators instead. E.g.
let taskURLString = "\(baseURL)\(typeItem)\(itemID)\(URLSuffix)"