I am new to Swift. I tried with this Swift link Detect a Null value in NSDictionaryNSDictionary, but I failed to do so.
Data:
"end_time" = "<null>"
Here is my code:
if endTime["end_time"] is NSNull {
print("your session still available ")
}
else{
print("your session end \(endTime["end_time"])")
}
Every time it is going to else statement. May be I need to convert string to null or alternative solution. Could you help me please?
Thank you.
Here's how you check null in swift:
let time = endTime["end_time"]
if time != "<null>" {
print("time is not <null>")
}
else
{
print("time is <null>")
}
You can create a NilCheck controller to check nil or null for various datatypes. For example i have created a function to remove null [if any] from the dictionary and store the array of dictionary in Userdefaults. Please be free to ask your queries :)
func removeNilAndSaveToLocalStore(array : [[String:Any]]) {
var arrayToSave = [[String:Any]]()
for place in array {
var dict = [String:Any]()
dict["AreaId"] = NilCheck.sharedInstance.checkIntForNil(nbr: place["AreaId"]! as? Int)
dict["AreaNameAr"] = NilCheck.sharedInstance.checkStringForNil(str: place["AreaNameAr"]! as? String)
dict["AreaName"] = NilCheck.sharedInstance.checkStringForNil(str: place["AreaName"]! as? String)
dict["GovernorateId"] = NilCheck.sharedInstance.checkIntForNil(nbr: place["GovernorateId"]! as? Int)
arrayToSave.append(dict)
}
LocalStore.setAreaList(token: arrayToSave)
}
class NilCheck {
static let sharedInstance : NilCheck = {
let instance = NilCheck()
return instance
}()
func checkStringForNil(str : String?) -> String {
guard let str = str else {
return String() // return default string
}
return str
}
func checkIntForNil(nbr : Int?) -> Int {
guard let num = nbr else {
return 0 // return default Int
}
return num
} }
Related
I am getting data from different sources, the variable could be a number or a string of number. How do I make sure that "(number as? NSString)" or "(number as? NSNumber)" always success? Something similar to Java optInt, which will never fail even if the number is a String. See example below:
func testNumber()
{
var number = 123
guard let a = (number as? NSNumber)?.intValue else { print("1");return; }
}
func testNumberString()
{
var number = "123"
guard let a = (number as? NSNumber)?.intValue else { print("2");return; } // this failed.
}
func testNumberToString()
{
var number = 123
guard let a = (number as? NSString)?.intValue else { print("2");return; } // this sometimes failed too depend on datasource.
}
As I understand from your question, you want an integer value at the end, no matter if the input type is string or integer.
You can achieve this by using ExpressibleByStringLiteral.
Here is the demo
extension Int: ExpressibleByStringLiteral {
public typealias StringLiteralType = String
public init(stringLiteral value: StringLiteralType) {
self = Int(value) ?? 0
}
}
This Int extension allows you to accept string value as Int and return int value. If it did not convert it will give you 0 by default.
Example
func testInt() {
let numberOne: Int = "5656"
let numberTwo: Int = 1234
print(numberOne)
print(numberTwo)
}
Or another way is to create your own ExpressibleByStringLiteral, which helps you to give default value as you want.
struct StringInt: ExpressibleByStringLiteral {
var value: Int?
init(stringLiteral value: String) {
self.value = Int("\(value)")
}
func wrapped(with defaultValue: Int) -> Int {
return self.value ?? defaultValue
}
}
Example
func testInt() {
var numberThree: StringInt = "5656"
print(numberThree.value as Any) // with nil or optional value
numberThree = "asf"
print(numberThree.wrapped(with: 15)) // with default value
/**
Output
Optional(5656)
15
*/
}
This fails (Non-nominal type 'Any' cannot be extended)
extension Any {
func literal() -> String {
if let booleanValue = (self as? Bool) {
return String(format: (booleanValue ? "true" : "false"))
}
else
if let intValue = (self as? Int) {
return String(format: "%d", intValue)
}
else
if let floatValue = (self as? Float) {
return String(format: "%f", floatValue)
}
else
if let doubleValue = (self as? Double) {
return String(format: "%f", doubleValue)
}
else
{
return String(format: "<%#>", self)
}
}
}
as I would like to use it in a dictionary (self) to xml string factory like
extension Dictionary {
// Return an XML string from the dictionary
func xmlString(withElement element: String, isFirstElement: Bool) -> String {
var xml = String.init()
if isFirstElement { xml.append("<?xml version=\"1.0\" encoding=\"utf-8\"?>\n") }
xml.append(String(format: "<%#>\n", element))
for node in self.keys {
let value = self[node]
if let array: Array<Any> = (value as? Array<Any>) {
xml.append(array.xmlString(withElement: node as! String, isFirstElemenet: false))
}
else
if let dict: Dictionary<AnyHashable,Any> = (value as? Dictionary<AnyHashable,Any>) {
xml.append(dict.xmlString(withElement: node as! String, isFirstElement: false))
}
else
{
xml.append(String(format: "<%#>", node as! CVarArg))
xml.append((value as Any).literal
xml.append(String(format: "</%#>\n", node as! CVarArg))
}
}
xml.append(String(format: "</%#>\n", element))
return xml.replacingOccurrences(of: "&", with: "&", options: .literal, range: nil)
}
}
I was trying to reduce the code somehow, as the above snippet is repeated a few times in a prototype I'm building but this is not the way to do it (a working copy with the snippet replicated works but ugly?).
Basically I want to generate a literal for an Any value - previously fetched from a dictionary.
It seems like you can't add extensions to Any. You do have some other options though - either make it a function toLiteral(value: Any) -> String, or what is probably a neater solution; use the description: String attribute which is present on all types that conform to CustomStringConvertible, which includes String, Int, Bool, and Float - your code would be simplified down to just xml.append(value.description). You then just have make a simple implementation for any other types that you might get.
Ok, finally got this working. First the preliminaries: each of your objects needs to have a dictionary() method to marshal itself. Note: "k.###" are struct static constants - i.e., k.name is "name", etc. I have two objects, a PlayItem and a PlayList:
class PlayItem : NSObject {
var name : String = k.item
var link : URL = URL.init(string: "http://")!
var time : TimeInterval
var rank : Int
var rect : NSRect
var label: Bool
var hover: Bool
var alpha: Float
var trans: Int
var temp : String {
get {
return link.absoluteString
}
set (value) {
link = URL.init(string: value)!
}
}
func dictionary() -> Dictionary<String,Any> {
var dict = Dictionary<String,Any>()
dict[k.name] = name
dict[k.link] = link.absoluteString
dict[k.time] = time
dict[k.rank] = rank
dict[k.rect] = NSStringFromRect(rect)
dict[k.label] = label ? 1 : 0
dict[k.hover] = hover ? 1 : 0
dict[k.alpha] = alpha
dict[k.trans] = trans
return dict
}
}
class PlayList : NSObject {
var name : String = k.list
var list : Array <PlayItem> = Array()
func dictionary() -> Dictionary<String,Any> {
var dict = Dictionary<String,Any>()
var items: [Any] = Array()
for item in list {
items.append(item.dictionary())
}
dict[k.name] = name
dict[k.list] = items
return dict
}
}
Note any value so marshal has to be those legal types for a dictionary; it helps to have aliases so in the PlayItem a "temp" is the string version for the link url, and its getter/setter would translate.
When needed, like the writeRowsWith drag-n-drop tableview handler, I do this:
func tableView(_ tableView: NSTableView, writeRowsWith rowIndexes: IndexSet, to pboard: NSPasteboard) -> Bool {
if tableView == playlistTableView {
let objects: [PlayList] = playlistArrayController.arrangedObjects as! [PlayList]
var items: [PlayList] = [PlayList]()
var promises = [String]()
for index in rowIndexes {
let item = objects[index]
let dict = item.dictionary()
let promise = dict.xmlString(withElement: item.className, isFirstElement: true)
promises.append(promise)
items.append(item)
}
let data = NSKeyedArchiver.archivedData(withRootObject: items)
pboard.setPropertyList(data, forType: PlayList.className())
pboard.setPropertyList(promises, forType:NSFilesPromisePboardType)
pboard.writeObjects(promises as [NSPasteboardWriting])
}
else
{
let objects: [PlayItem] = playitemArrayController.arrangedObjects as! [PlayItem]
var items: [PlayItem] = [PlayItem]()
var promises = [String]()
for index in rowIndexes {
let item = objects[index]
let dict = item.dictionary()
let promise = dict.xmlString(withElement: item.className, isFirstElement: true)
promises.append(promise)
items.append(item)
}
let data = NSKeyedArchiver.archivedData(withRootObject: items)
pboard.setPropertyList(data, forType: PlayList.className())
pboard.setPropertyList(promises, forType:NSFilesPromisePboardType)
pboard.writeObjects(promises as [NSPasteboardWriting])
}
return true
}
What makes this happen are these xmlString extensions and the toLiteral function - as you cannot extend "Any":
func toLiteral(_ value: Any) -> String {
if let booleanValue = (value as? Bool) {
return String(format: (booleanValue ? "1" : "0"))
}
else
if let intValue = (value as? Int) {
return String(format: "%d", intValue)
}
else
if let floatValue = (value as? Float) {
return String(format: "%f", floatValue)
}
else
if let doubleValue = (value as? Double) {
return String(format: "%f", doubleValue)
}
else
if let stringValue = (value as? String) {
return stringValue
}
else
if let dictValue: Dictionary<AnyHashable,Any> = (value as? Dictionary<AnyHashable,Any>)
{
return dictValue.xmlString(withElement: "Dictionary", isFirstElement: false)
}
else
{
return ((value as AnyObject).description)
}
}
extension Array {
func xmlString(withElement element: String, isFirstElemenet: Bool) -> String {
var xml = String.init()
xml.append(String(format: "<%#>\n", element))
self.forEach { (value) in
if let array: Array<Any> = (value as? Array<Any>) {
xml.append(array.xmlString(withElement: "Array", isFirstElemenet: false))
}
else
if let dict: Dictionary<AnyHashable,Any> = (value as? Dictionary<AnyHashable,Any>) {
xml.append(dict.xmlString(withElement: "Dictionary", isFirstElement: false))
}
else
{
xml.append(toLiteral(value))
}
}
xml.append(String(format: "<%#>\n", element))
return xml
}
}
extension Dictionary {
// Return an XML string from the dictionary
func xmlString(withElement element: String, isFirstElement: Bool) -> String {
var xml = String.init()
if isFirstElement { xml.append("<?xml version=\"1.0\" encoding=\"utf-8\"?>\n") }
xml.append(String(format: "<%#>\n", element))
for node in self.keys {
let value = self[node]
if let array: Array<Any> = (value as? Array<Any>) {
xml.append(array.xmlString(withElement: node as! String, isFirstElemenet: false))
}
else
if let dict: Dictionary<AnyHashable,Any> = (value as? Dictionary<AnyHashable,Any>) {
xml.append(dict.xmlString(withElement: node as! String, isFirstElement: false))
}
else
{
xml.append(String(format: "<%#>", node as! CVarArg))
xml.append(toLiteral(value as Any))
xml.append(String(format: "</%#>\n", node as! CVarArg))
}
}
xml.append(String(format: "</%#>\n", element))
return xml
}
func xmlHTMLString(withElement element: String, isFirstElement: Bool) -> String {
let xml = self.xmlString(withElement: element, isFirstElement: isFirstElement)
return xml.replacingOccurrences(of: "&", with: "&", options: .literal, range: nil)
}
}
This continues another's solution, the toLiteral() suggestion above, in hopes it helps others.
Enjoy.
I am getting error while migrating to Swift 3. Below is the code in which error comes.
func getProfileFieldValue(_ formFields:NSMutableArray,keyValue:String) -> String {
for key in formFields{
if keyValue == key["name"] as! String{
return key["value"] as! String
}
}
return ""
}
Please help and thanks in advance.
NSMutableArray does not provide any type information, use native Swift array
func getProfileFieldValue(_ formFields:[[String:Any]], keyValue: String) -> String {
for key in formFields {
if let value = key["name"] as? String, value == keyValue {
return key["value"] as! String
}
}
return ""
}
or if the dictionaries contain only String values
func getProfileFieldValue(_ formFields:[[String:String]], keyValue: String) -> String {
for key in formFields {
if let value = key["name"], value == keyValue {
return key["value"]!
}
}
return ""
}
Or still swiftier
func getProfileFieldValue(_ formFields:[[String:Any]], keyValue: String) -> String {
if let profileField = formFields.first(where { $0["name"] as? String == keyValue }) {
return profileField["value"] as! String
}
return ""
}
Finally the waterproof-will-never-crash version:
func getProfileFieldValue(_ formFields:[[String:Any]], keyValue: String) -> String {
guard let profileField = formFields.first(where: { $0["name"] as? String == keyValue }),
let value = profileField["value"] as? String else { return "" }
return value
}
NSMutableArray does not provide type information, so you'll need to cast the array prior to the for loop
let array = NSMutableArray(array: [1, 2, 3, 4, 5])
let keyValue = 3
for item in array as! [Int]
{
if keyValue == item
{}
}
I'm using socket.io Swift Library. With the following line of code,
socket.on("info") { (dataArray, socketAck) -> Void in
let user = dataArray[0] as? User
print(user._id)
}
dataArray[0] is a valid object but user appears to be nil after casting.
Since dataArray[0] returns as an AnyObject,
how can i cast AnyObject to User Object?. Or somehow manage to do what i want with a different approach?
Since after this line
let user = dataArray[0] as? User
you have a nil value inside user it means that you don't have a User value at the first position of dataArray.
Since dataArray comes from a server (as I guess) it probably contains a serialized version of User.
Now we really need to know what really dataArray[0] is. However...
if dataArray[0] contains NSData
In this case try this
let json = JSON(dataArray[0] as! NSData)
let user = User(json:json)
You need to create a constructor that accept AnyObject and read data in it.
I guess in this case dataArray[0] is an JSON Object.
class User {
init(data: [String: AnyObject]) {
username = data["username"] as? String ?? ""
}
}
This is how i manage mine:
// Structure used as parameter
struct InfoStruct {
var nome: String = ""
var sobrenome:String = ""
var nascimentoTimestamp: NSNumber = 0
init() {
}
// Struct to AnyObject
func toAnyObject() -> Any {
var dic = [String:AnyObject?]()
if (nome != "") { dic["nome"] = nome as AnyObject }
if (sobrenome != "") { dic["sobrenome"] = sobrenome as AnyObject }
if (nascimentoTimestamp != 0) { dic["nascimentoTimestamp"] = nascimentoTimestamp as AnyObject }
return dic
}
// AnyObject to Struct
func fromAnyObject(dic:[String:AnyObject]) -> InfoStruct {
var retorno = InfoStruct()
if (dic["nome"] != nil) { retorno.nome = dic["nome"] as? String ?? "" }
if (dic["sobrenome"] != nil) { retorno.sobrenome = dic["sobrenome"] as? String ?? "" }
if (dic["nascimentoTimestamp"] != nil) { retorno.nascimentoTimestamp = dic["nascimentoTimestamp"] as? NSNumber ?? 0 }
return retorno
} }
// User class
class Usuario: NSObject {
var key: String
var admin: Bool
var info: InfoStruct // Struct parameter
init(_ key: String?) {
self.key = key ?? ""
admin = false
info = InfoStruct() // Initializing struct
}
// From Class to AnyObject
func toAnyObject() -> Any {
var dic = [String:AnyObject?]()
if (key != "") { dic["key"] = key as AnyObject }
if (admin != false) { dic["admin"] = admin as AnyObject }
dic["info"] = info.toAnyObject() as AnyObject // Struct
return dic
}
// From AnyObject to Class
func fromAnyObject(dic:[String:AnyObject]) -> Usuario {
let retorno = Usuario(dic["key"] as? String)
if (dic["key"] != nil) { retorno.key = dic["key"] as? String ?? "" }
if (dic["admin"] != nil) { retorno.admin = dic["admin"] as? Bool ?? false }
if (dic["info"] != nil) { retorno.info = InfoStruct.init().fromAnyObject(dic: dic["info"] as! [String : AnyObject]) } // Struct
return retorno
} }
// Using
let dao = FirebaseDAO.init(_type: FirebaseDAOType.firebaseDAOTypeUser)
dao.loadValue(key: uid) { (error, values:[String : AnyObject]) in
if error == nil {
let user = Usuario(values["key"] as? String).fromAnyObject(dic: values)
}
}
I hope it helps!
I have a swift struct named Product which takes a Dictionary in its init method. I want to compute a price value in a local Price struct within my Product. I want this value to be a let constant since it won't ever change, but swift won't allow me to do that without using var, saying that the let constant is not properly initialized.
How can I make my value property inside my Price struct a let constant in this case?
struct Product {
let price: Price
init(dictionary: Dictionary<String, AnyObject>) {
if let tmp = dictionary["price"] as? Dictionary<String, AnyObject> { price = Price(dictionary: tmp) } else { price = Price() }
}
struct Price {
var value = ""
init() {
}
init(dictionary: Dictionary<String, AnyObject>) {
if let xForY = dictionary["xForY"] as? Array<Int> {
if xForY.count == 2 {
value = "\(xForY[0]) for \(xForY[1])"
}
}
if let xForPrice = dictionary["xForPrice"] as? Array<Int> {
if value == "" && xForPrice.count == 2 {
value = "\(xForPrice[0]) / \(xForPrice[1]):-"
}
}
if let reduced = dictionary["reduced"] as? String {
if value == "" {
value = "\(reduced):-"
}
}
}
}
}
You have to rewrite the code so that the compiler gets what you intend to do actually. It is not clever enough to deduce it from the way you coded it.
I would also suggest that you make the initializer for the Price struct failable instead of using an empty string for the value property. As a consequence of that change the price property of the Product struct becomes an optional.
struct Product {
let price: Price?
init(dictionary: Dictionary<String, AnyObject>) {
if let tmp = dictionary["price"] as? Dictionary<String, AnyObject> {
price = Price(dictionary: tmp)
}
else {
price = nil
}
}
struct Price {
let value : String
init?(dictionary: Dictionary<String, AnyObject>) {
if let xForY = dictionary["xForY"] as? Array<Int> where xForY.count == 2 {
value = "\(xForY[0]) for \(xForY[1])"
}
else if let xForPrice = dictionary["xForPrice"] as? Array<Int> where xForPrice.count == 2 {
value = "\(xForPrice[0]) / \(xForPrice[1]):-"
}
else if let reduced = dictionary["reduced"] as? String {
value = "\(reduced):-"
}
else {
return nil
}
}
}
}
The trouble is that (1) you're assigning to value in the declaration, (2) you're not assigning a value in init(), and (3) you're referencing and reassigning value in init([String: AnyObject]). You can only assign a value to a constant once and can only reference its value after its been assigned to.
To fix the issue, you can either make your property publicly readonly:
private(set) var value: String = ""
Or you can use a second variable inside your init:
struct Price {
let value: String
init() {
self.value = ""
}
init(dictionary: Dictionary<String, AnyObject>) {
var v: String = ""
if let xForY = dictionary["xForY"] as? Array<Int> {
if xForY.count == 2 {
v = "\(xForY[0]) for \(xForY[1])"
}
}
if let xForPrice = dictionary["xForPrice"] as? Array<Int> {
if v == "" && xForPrice.count == 2 {
v = "\(xForPrice[0]) / \(xForPrice[1]):-"
}
}
if let reduced = dictionary["reduced"] as? String {
if v == "" {
v = "\(reduced):-"
}
}
self.value = v
}
}