I'm having a array of CNContact and I sort them with this function:
for contact in self.contacts {
var contactName = contact.organizationName
let key: String = String(contactName.characters.first).uppercaseString
if let arrayForLetter = self.contactDictionary[key] {
self.contactDictionary[key]!.append(contact)
self.contactDictionary.updateValue(arrayForLetter, forKey: key)
} else {
self.contactDictionary.updateValue([contact], forKey: key)
}
}
self.keys = self.contactDictionary.keys.sort()
Where contactDictionary is of type:
var contactDictionary: [String: [CNContact]] = [String: [CNContact]]()
var keys: [String] = []
Now when I see the contactDictionary when it's filled it works except the key always Optional(\"T"\") or some other letter of course. But why is it optional? The key in the forloop is not optional so how does this come?
first property of Collection is of optional type, So you are getting optional probably here contactName.characters.first, if you wrapped it using if let or guard will solved your issue.
if let fc = name.characters.first {
let key = String(fc).uppercaseString
}
Try to do it this way:
for contact in self.contacts {
var contactName = contact.organizationName
if let key = String(contactName.characters.first).uppercaseString {
if let arrayForLetter = self.contactDictionary[key] {
self.contactDictionary[key]!.append(contact)
self.contactDictionary.updateValue(arrayForLetter, forKey: key)
} else {
self.contactDictionary.updateValue([contact], forKey: key)
}
}
}
self.keys = self.contactDictionary.keys.sort()
Related
I am trying to append to an NSMutableDictionary with the following code:
let RSVPDirectory = NSMutableDictionary()
for i in 0..<self.RSVPs.count {
var tmp = self.RSVPs[i]
var firstLetter = String()
if(tmp["lastname"] is NSNull)
{
firstLetter = ((tmp["email"] as? NSString)?.substring(to: 1).uppercased())!
}
else
{
firstLetter = ((tmp["lastname"] as? NSString)?.substring(to: 1).uppercased())!
}
if RSVPDirectory[firstLetter] == nil {
RSVPDirectory[firstLetter] = [AnyHashable]()
}
RSVPDirectory[firstLetter] = tmp
}
My problem with this is that I am expecting multiple tmp inside RSVPDirectory[firstLetter] but it only adds the first one as if its overriding the previous tmp
How do I append to NSMutableDictionary in swift, I know in objective-c you can do this:
[[RSVPDirectory objectForKey:firstLetter] addObject:tmp];
What would be the equivalent to that in swift?
Try the below code in a playground you will see the output, hope this gives you an idea.
func upperCaseFirstLetter(_ str: String) -> String {
guard let first = str.first else { return "" }
return "\(first)".uppercased()
}
var RSVPs = [[String:String]]()
var RSVPDirectory = [String: [[String:String]]]()
//Test Data
var str = ["email":"test1#c.com"]
RSVPs.append(str)
str = ["lastname":"Atest2"]
RSVPs.append(str)
for i in 0..<RSVPs.count {
var tmp = RSVPs[i]
var firstLetter = ""
if(tmp["lastname"] == nil) {
firstLetter = upperCaseFirstLetter(tmp["email"]!)
} else {
firstLetter = upperCaseFirstLetter(tmp["lastname"]!)
}
if RSVPDirectory[firstLetter] == nil {
RSVPDirectory[firstLetter] = [[String:String]]()
}
RSVPDirectory[firstLetter]?.append(tmp)
}
print(RSVPDirectory)
This is the native Swift version of your Objective-C-ish code.
It uses the Dictionary(grouping API of Swift 4
let RSVPDirectory = Dictionary(grouping: RSVPs) { (dictionary) -> String in
if let lastName = dictionary["lastname"] as? String {
return String(lastName.prefix(1).uppercased())
} else if let email = dictionary["email"] as? String {
return String(email.prefix(1).uppercased())
} else {
return "🚫"
}
}
Yes you are actually replacing the RSVPDirectory[firstLetter], overriding it every time with new tmp.
What you are looking for is this:
//RSVPDirectory[firstLetter] = tmp //Replace this line with below code
let tempArray = RSVPDirectory[firstLetter] as? [AnyHashable]
tempArray?.append(tmp)
RSVPDirectory[firstLetter] = tmpArray
Here I have used a tempArray because we want to mutate the array. Accessing it directly and trying to append new value will in-turn try to mutate an immutable value. So first I have got the array in the tempArray and then after mutating the array I swapped it back in the dictionary with updated values.
In my object Dish xxx.Dish, I want to access the Choice class price and name to display but I failed. dish data load from web API and I tested data loaded success full and put the data to the object dish and it return the object list to viewcontroller to load tableview.
Output of printed console
Optional([xxx.Dish, xxx.Dish])
and in the dish class before append optionList?.append(_obj)
xxx.DishOption
Anyone helps me how can I do that .. I am new to swift and is it right way to implement? Please suggest me?
class Dish {
let dishId : String
var optionList : [DishOption]?
init?(fromAPIResponse resposne : Dictionary<String,AnyObject>) {
guard let dishId = resposne["dishId"] as? String else {
return nil
}
self.dishId = dishId
if let objs = resposne["options"] as? [[String: AnyObject]]{
for obj in objs {
if let _obj = DishOption(fromAPIResponse: obj){
optionList?.append(_obj)
}
}
}
}
class DishOption {
let optionId : String
var choiceList : [Choice]?
init?(fromAPIResponse resposne : Dictionary<String,AnyObject>) {
guard let optionId = resposne["optionId"] as? String else {
return nil
}
self.optionId = optionId
if let objs = resposne["choices"] as? [[String: AnyObject]]{
for obj in objs {
if let _obj = Choice(fromAPIResponse: obj){
choiceList?.append(_obj)
}
}
}
}
}
class Choice{
let choiceId : String
let name : String
let price : String
init?(fromAPIResponse resposne : Dictionary<String,AnyObject>) {
guard let choiceId = resposne["choiceId"] as? String ,
let name = resposne["name"] as? String,
let price = resposne["price"] as? String else {
return nil
}
self.choiceId = choiceId
self.name = name
self.price = price
}
}
UPDATE:
var dishMenuList = [Dish]()
guard let objs = json["menu_list"] as? [[String : AnyObject]] else {
return
}
for obj in objs {
if let _obj = Dish(fromAPIResponse: obj){
print(_obj.optionList) //always print nil
if let options = _obj.optionList {
for data in options {
print(data.displayAsButton)
}
}
dishMenuList.append(_obj)
}
}
From what I can see, you are never initializing both the optionList and choiceList arrays. It would be better to initialize them as empty arrays:
class Dish {
let dishId : String
var optionList = [DishOption]()
...
optionList.append(_obj)
This is the reason that you cannot see any options. Since the optionList is still nil, the line optionList?.append(_obj) does not execute.
I am trying to add a key and a value to a dictionary then add this dictionary the user defaults and read back into a dictionary object. I have two questions that I would really appreciate any help in,
1) why is the dictionary being read from user defaults empty? Since I added a key and a value to the dictionary shouldn't those be saved to the dictionary I retrieve from user defaults?
let defaults = UserDefaults.standard;
var myDict = [String: String]()
myDict["key"] = "value"
defaults.setValue(myDict, forKey: "myDict")
let mydict2 = defaults.object(forKey: "myDict") as? [String: String] ?? [String:String]()
print(mydict2)
2) What can I do to this code if the dictionary stores a custom class that I created as a value or a key so if the dictionary was like this:
class Car {
var engineSize: Int
var color: String
init() {
engineSize = 2000
color = "blue"
}
}
class Boat {
var surfaceArea: Int
var weight: Int
init() {
surfaceArea = 3500
weight = 4000
}
}
var myDict = [Car: Boat]()
how can I save that second dict to user defaults and read it from there?
Thank you
EDIT:
This is the answer suggested by ebby94:
var myDict = [String:String]()
myDict["key"] = "value";
let data = NSKeyedArchiver.archivedData(withRootObject: myDict)
UserDefaults.standard.set(data, forKey: "myDict")
func foo()
{
guard let archivedData = UserDefaults.standard.value(forKey: "myDict") as? Data
else
{
print("failed1")
return
}
guard var unarchivedDictionary = NSKeyedUnarchiver.unarchiveObject(with: archivedData) as? [String:String]
else
{
print("failed2")
return
}
print(unarchivedDictionary["key"]!)
}
foo()
However this prints failed1, I'm assuming the data wasn't archived correctly. Can this be because I'm running it in playground?
If you want to save custom object to userDefault first you need to encode & decode variable then save using archive & get data using unarchive.
class Car {
var engineSize: Int
var color: String
init() {
engineSize = 2000
color = "blue"
}
// Decode
required convenience public init(coder decoder: NSCoder)
{
self.init()
if let engineSize = decoder.decodeObject(forKey: "engineSize") as? Int
{
self.engineSize = engineSize
}
if let color = decoder.decodeObject(forKey: "color") as? String
{
self.color = color
}
}
// Encode
func encodeWithCoder(coder : NSCoder)
{
if let engineSize = self.engineSize
{
coder.encode(engineSize, forKey: "engineSize")
}
if let color = self.color
{
coder.encode(color, forKey: "weight")
}
}
}
class Boat {
var surfaceArea: Int
var weight: Int
init() {
surfaceArea = 3500
weight = 4000
}
// Decode
required convenience public init(coder decoder: NSCoder)
{
self.init()
if let surfaceArea = decoder.decodeObject(forKey: "surfaceArea") as? Int
{
self.surfaceArea = surfaceArea
}
if let weight = decoder.decodeObject(forKey: "weight") as? Int
{
self.weight = weight
}
}
// Encode
func encodeWithCoder(coder : NSCoder)
{
if let surfaceArea = self.surfaceArea
{
coder.encode(surfaceArea, forKey: "surfaceArea")
}
if let weight = self.weight
{
coder.encode(weight, forKey: "weight")
}
}
You can't save a dictionary directly in UserDefaults. You'll have to convert the dictionary into data and save it and then retrieve the data and unarchive it into dictionary.
Archive and save to UserDefaults
let myDict = [String:String]()
let data = NSKeyedArchiver.archivedData(withRootObject: myDict)
UserDefaults.standard.set(data, forKey: "myDict")
Retrieve and unarchive the data to dictionary
guard let archivedData = UserDefaults.standard.value(forKey: "myDict") as? Data
else{return}
guard let unarchivedDictionary = NSKeyedUnarchiver.unarchiveObject(with: archivedData) as? [String:String]
else{return}
Userdefaults not work in Playground. you need to implement and start it in an App in Simulator
I have following code for dictionary
var dic : [String: AnyObject] = ["FirstName": "Anvar", "LastName": "Azizov", "Website": NSNull(),"About": NSNull()]
I already remove key which have null value using below code
var keys = dic.keys.array.filter({dic[$0] is NSNull})
for key in keys {
dic.removeValueForKey(key)
}
It works for static dictionary,But I want do it dynamically,I want to done it using function but whenever I pass dictionary as a argument it works as a let means constant so can not remove null key
I make below code for that
func nullKeyRemoval(dic : [String: AnyObject]) -> [String: AnyObject]{
var keysToRemove = dic.keys.array.filter({dic[$0] is NSNull})
for key in keysToRemove {
dic.removeValueForKey(key)
}
return dic
}
please tell me solution for this
Rather than using a global function (or a method), why not making it a method of Dictionary, using an extension?
extension Dictionary {
func nullKeyRemoval() -> Dictionary {
var dict = self
let keysToRemove = Array(dict.keys).filter { dict[$0] is NSNull }
for key in keysToRemove {
dict.removeValue(forKey: key)
}
return dict
}
}
It works with any generic types (so not limited to String, AnyObject), and you can invoke it directly from the dictionary itself:
var dic : [String: AnyObject] = ["FirstName": "Anvar", "LastName": "Azizov", "Website": NSNull(),"About": NSNull()]
let dicWithoutNulls = dic.nullKeyRemoval()
Swift 5 adds compactMapValues(_:), which would let you do
let filteredDict = dict.compactMapValues { $0 is NSNull ? nil : $0 }
For Swift 3.0 / 3.1 this could be helpful. Also removes NSNull objects recursive:
extension Dictionary {
func nullKeyRemoval() -> [AnyHashable: Any] {
var dict: [AnyHashable: Any] = self
let keysToRemove = dict.keys.filter { dict[$0] is NSNull }
let keysToCheck = dict.keys.filter({ dict[$0] is Dictionary })
for key in keysToRemove {
dict.removeValue(forKey: key)
}
for key in keysToCheck {
if let valueDict = dict[key] as? [AnyHashable: Any] {
dict.updateValue(valueDict.nullKeyRemoval(), forKey: key)
}
}
return dict
}
}
Swift 3+: Remove null from dictionary
func removeNSNull(from dict: [String: Any]) -> [String: Any] {
var mutableDict = dict
let keysWithEmptString = dict.filter { $0.1 is NSNull }.map { $0.0 }
for key in keysWithEmptString {
mutableDict[key] = ""
}
return mutableDict
}
Use:
let outputDict = removeNSNull(from: ["name": "Foo", "address": NSNull(), "id": "12"])
Output: ["name": "Foo", "address": "", "id": "12"]
Nested NSNull supported
To remove any NSNull appearance in any nested level (including arrays and dictionaries), try this:
extension Dictionary where Key == String {
func removeNullsFromDictionary() -> Self {
var destination = Self()
for key in self.keys {
guard !(self[key] is NSNull) else { destination[key] = nil; continue }
guard !(self[key] is Self) else { destination[key] = (self[key] as! Self).removeNullsFromDictionary() as? Value; continue }
guard self[key] is [Value] else { destination[key] = self[key]; continue }
let orgArray = self[key] as! [Value]
var destArray: [Value] = []
for item in orgArray {
guard let this = item as? Self else { destArray.append(item); continue }
destArray.append(this.removeNullsFromDictionary() as! Value)
}
destination[key] = destArray as? Value
}
return destination
}
}
Swift 4
A little more efficient than the other solutions. Uses only O(n) complexity.
extension Dictionary where Key == String, Value == Any? {
var trimmingNullValues: [String: Any] {
var copy = self
forEach { (key, value) in
if value == nil {
copy.removeValue(forKey: key)
}
}
return copy as [Key: ImplicitlyUnwrappedOptional<Value>]
}
}
Usage: ["ok": nil, "now": "k", "foo": nil].trimmingNullValues // =
["now": "k"]
If your dictionary is mutable you could do this in place and prevent the inefficient copying:
extension Dictionary where Key == String, Value == Any? {
mutating func trimNullValues() {
forEach { (key, value) in
if value == nil {
removeValue(forKey: key)
}
}
}
}
Usage:
var dict: [String: Any?] = ["ok": nil, "now": "k", "foo": nil]
dict.trimNullValues() // dict now: = ["now": "k"]
The cleanest way to do it, just 1 line
extension Dictionary {
func filterNil() -> Dictionary {
return self.filter { !($0.value is NSNull) }
}
}
Rather than using a global function (or a method), why not making it a method of Dictionary, using an extension?
extension NSDictionary
{
func RemoveNullValueFromDic()-> NSDictionary
{
let mutableDictionary:NSMutableDictionary = NSMutableDictionary(dictionary: self)
for key in mutableDictionary.allKeys
{
if("\(mutableDictionary.objectForKey("\(key)")!)" == "<null>")
{
mutableDictionary.setValue("", forKey: key as! String)
}
else if(mutableDictionary.objectForKey("\(key)")!.isKindOfClass(NSNull))
{
mutableDictionary.setValue("", forKey: key as! String)
}
else if(mutableDictionary.objectForKey("\(key)")!.isKindOfClass(NSDictionary))
{
mutableDictionary.setValue(mutableDictionary.objectForKey("\(key)")!.RemoveNullValueFromDic(), forKey: key as! String)
}
}
return mutableDictionary
}
}
Swift 4 example using reduce
let dictionary = [
"Value": "Value",
"Nil": nil
]
dictionary.reduce([String: String]()) { (dict, item) in
guard let value = item.value else {
return dict
}
var dict = dict
dict[item.key] = value
return dict
}
I'm trying to use reflection in Swift with Core Data entities, but when I execute the following code, my reflected var has only a reference for a super class, it didn't have a reference for any of it's attributes.
func printProperties() {
let mirror = reflect(self)
for var i = 0; i < mirror.count; i++ {
let (propertyName, childMirror) = mirror[i]
println("property name: \(propertyName)")
println("property value: \(childMirror.value)")
}
}
Does anyone have some idea why this happens?
Update: As suggested by Anderson in his answer I tried another approach and ended up with this code:
func loadFromJson(json: JSON) {
for attributeKey in self.entity.attributesByName.keys {
let attributeDescription = self.entity.propertiesByName[attributeKey]!
as! NSAttributeDescription
let attributeClassName = attributeDescription.attributeValueClassName
let jsonValue = json[(attributeKey as! String)]
var attributeValue: AnyObject? = attributeDescription.defaultValue
if jsonValue.type != .Null && attributeClassName != nil {
if attributeClassName == "NSNumber" {
attributeValue = jsonValue.number!
} else if attributeClassName == "NSString" {
attributeValue = jsonValue.string!
}
}
setValue(attributeValue, forKey: (attributeKey as! String))
}
}
I believe that this code can help you.
I wrote this extension to make a dictionary from a NSmanagedObject and it accesses all attributes and values of the object.
extension NSManagedObject {
func toDict() -> Dictionary<String, AnyObject>! {
let attributes = self.entity.attributesByName.keys
let relationships = self.entity.relationshipsByName.keys
var dict: [String: AnyObject] = [String: AnyObject]()
var dateFormater = NSDateFormatter()
dateFormater.dateFormat = "yyyy-MM-dd'T'HH:mm:ss"
for attribute in attributes {
if self.entity.propertiesByName[attribute]!.attributeValueClassName != nil && self.entity.propertiesByName[attribute]!.attributeValueClassName == "NSDate" {
let value: AnyObject? = self.valueForKey(attribute as! String)
if value != nil {
dict[attribute as! String] = dateFormater.stringFromDate(value as! NSDate)
} else {
dict[attribute as! String] = ""
}
} else {
let value: AnyObject? = self.valueForKey(attribute as! String)
dict[attribute as! String] = value
}
}
for attribute in relationships {
let relationship: NSManagedObject = self.valueForKey(attribute as! String) as! NSManagedObject
let value = relationship.valueForKey("key") as! String
dict[attribute as! String] = value
}
return dict
}
}
I hope to have helped you.