I am assigning UserInfo Dictionary from NSUserDefault as NSMutableDictionary.
Now my dicInfo is mutable dictionary, but object it contains are immutable.
So, when i am trying to replace those value it cause crash.
I am attaching image which describe crash report.
If any solution, to how to convert inner object of mutable dictionary to mutable.
Thanks
The NSDictionary class conforms to the NSMutableCopying protocol. As such, we can call the mutableCopy method on an NSDictionary to get an NSMutableDictionary copy of the object.
let dicInfo = userSharedDefaults?.objectForKey(UserDefaultKey.kUserBasicInfo) as? NSDictionary
let mutableDictionary = dicInfo?.mutableCopy
In Swift, we may need to cast this as the correct type:
let mutableDictionary = dicInfo?.mutableCopy as? NSMutableDictionary
var dicInfo = (userSharedDefault.object(forKey: "kUserbasicInfo") as! NSDictionary).mutableCopy() as! NSMutableDictionary
You can also create Mutable Dictionary as follows:
It will fix the crash.
let dicInfo = NSMutableDictionary.init(dictionary: userSharedDefaults?.objectForKey(UserDefaultKey.kUserBasicInfo) as! NSDictionary)
Neither use NSMutableDictionary nor mutableCopy() in Swift to get a mutable dictionary from UserDefaults.
Never do that.
Normally far be it from me to criticize other answers but NSMutableDictionary and mutableCopy() are indeed inappropriate API in Swift.
To get a dictionary from UserDefaults use dedicated method dictionary(forKey:. The default dictionary type is [String:Any]
To make an object mutable simply use the var keyword
var userbasicInfo : [String:Any]
if let dictionary = UserDefaults.standard.dictionary(forKey: UserDefaultKey.kUserBasicInfo) {
userbasicInfo = dictionary
} else {
userbasicInfo = [String:Any]()
}
userbasicInfo[kPin] = 5678
print(userbasicInfo)
UserDefaults.standard.set(userbasicInfo, forKey:UserDefaultKey.kUserBasicInfo)
Related
To save some data to UserDefaults first we must encode it as JSON using JSONEncoder, which will send back a Data instance we can send straight to UserDefaults.Then reading saved data is a matter of converting from Data using a JSONDecoder. But sometimes we dont have to do that.
My question is will that method work anytime and when do i have to use it because i found this other solution without encode and decode:
var allWords = [String]()
var usedWords = [String]()
var currentWord: String?
In viewDidLoad:
let defaults = UserDefaults.standard
if let presentWord = defaults.object(forKey: "presentWord") as? String,
let savedWords = defaults.object(forKey: "savedWords") as? [String] {
title = presentWord
currentWord = presentWord
usedWords = savedWords
print("Loaded old game!")
Save method:
func save() {
let defaults = UserDefaults.standard
defaults.set(currentWord, forKey: "presentWord")
defaults.set(usedWords, forKey: "savedWords")
}
It's simple and faster way but Im not sure when i can use it with no worries
UserDefaults storage is a property list. NSString, NSData, NSArray, and NSDictionary are the only Cocoa classes that can be expressed directly in a property list. Moreover, an NSArray or NSDictionary can be expressed in a property list only if its elements are instances of those classes, along with NSDate and NSNumber. Those are the property list types.
If your Swift type bridges to a property list type, you can store it directly. So String will bridge to NSString, and an array of String will bridge to an NSArray of NSString, so you can store them directly.
But if what you've got is not a property list type, you need to transform it into a property list type before you can store it, and the usual solution is to transform it into an NSData (Swift Data). You don't have to use JSONEncoder for that but you do need to do it somehow.
I would like to save an array of object in my UserDefaults
let thisAction = action(ts: String(Date().timeStamp()), winner: winner)
actions.append(thisAction)
UserDefaults.standard.set(actions, forKey: "currentMatch")
UserDefaults.standard.synchronize()
But I have the following error:
Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Attempt to insert non-property list object
Try Objective-C objects (NSArray, NSDictionary).
https://developer.apple.com/library/content/documentation/Cocoa/Conceptual/UserDefaults/AccessingPreferenceValues/AccessingPreferenceValues.html#//apple_ref/doc/uid/10000059i-CH3-97383 .
It is stated that objects of types NSData, NSDate, NSString, NSNumber, NSArray, NSDictionary, and NSURL can be saved, got.
So, a possible solution is:
struct Action { var timestamp: TimeInterval; var winner: String }
var actions: [Action] = []
...
actions.map({ ["time": $0.timestamp, "winner": $0.winner ] as NSDictionary })
// You could also convert the actions manually one by one into NSDictionary
// and append them to an [NSDictionary]
UserDefaults.standard.set(actions as NSArray, forKey: "currentMatch")
UserDefaults.standard.synchronize()
Swift arrays and dictionary can be bridged to NSArray, NSDictionary respectively.
You can also use Codable, it can serialize property lists also.
I have saved an array of custom objects that conforms to NSCoding protocol in UserDefaults using NSKeyedArchiver. But when I try to retrieve it using NSKeyedUnarchiver, i get runtime errors from Xcode. I have tried initialising NSArray using unarchived data but it also failed. My guess is that while unarchiving swift doesn't understand custom elements of this array. How shall I do it?
This is how I archived array of custom objects
static func saveCategoryList(_ categoryList : [Category]!) -> Void{
let userDefaults = UserDefaults.standard
let categoryListData = NSKeyedArchiver.archivedData(withRootObject: categoryList)
userDefaults.set(categoryListData, forKey: Constants.CategoryList)
userDefaults.synchronize()
}
I get error like the attached screenshot in runtime. I am quite sure I am not doing it right. How can get my desired result?
I'm trying to migrate an objc project to swift3. I'm not sure how can I compare an array to nil. I have found this topic, but that was 2 years ago and the swift's syntax has changed a lot.
If I have a code like this in swift:
let variable = something as? NSArray
if variable == nil {
// do something
}
It won't let me to compare this variable with nil, causing an error "comparing this variable, always returns false". I have tried comparing variable.description with " ", but does it do the same thing?
By "something" i meant:
var variable = dict.object(forKey: someString) as! NSArray
The main thing I wanted to do with this was:
var variable = dict.object(forKey: someString) as! NSArray
if variable == nil {
//create
}
else {
// append
}
That's what the optional unwrapping syntax is for. You can combine the unwrapping and cast into one if statement:
if let variable = something as? NSArray {
// variable is not nil and is an NSArray
// Now you can do something with it.
} else {
// Either something is nil or it is not able to be cast as an NSArray
// Handle this case.
}
I should also mention that if you don't need to use something in Objective-C, then you should use the Swift-native array type. This can be declared like this:
let someArray = ["string1", "string2"]
This line indicates that variable is and must be an NSArray. If dict.object(forKey: someString) is not an NSArray, this will cause a crash
var variable = dict.object(forKey: someString) as! NSArray
// ^
// This exclamation mark means you are certain this is an NSArray
// Also, because there is no question mark after NSArray, this variable
// is not optional. It cannot be nil
However, you then use
if variable == nil {
And this is where the warning comes from. The variable can never be nil, because the variable is not optional
What you probably want is:
if let variable = dict.object(forKey:someString) as? NSArray
This will return false if:
dict.object(forKey:someString) returns a nil object
the object returned is not an NSArray
After this variable is now a non-optional NSArray. It is guaranteed to be an NSArray and is guaranteed to not be nil. You can use it without unwrapping it. e.g.
if let variable = dict.object(forKey:someString) as? NSArray {
for element in variable {
}
}
else {
//The dict doesn't contain the object yet. `variable` is nil
//Create a new array and add it to dict
let newArray = ["First Value"]
dict[someString] = newArray
}
let variable = something as? NSArray
With this declaration, variable will be an optional type (NSArray?) and never nil. This is because casting with as? returns an optional value that either contains the successfully casted object or nothing. You can see this by alt-clicking the variable name in Xcode.
If you want to know whether it contains a value, you need to use the if let syntax:
if let variable = variable {
// variable is guaranteed to be an NSArray here.
}
You can also use this format with guard-else:
guard let variable = something as? NSArray else {
// your variable is nil. Do something if needed
}
// your variable is available in this scope. Do something when variable contains Array
I've got a really weird error while running my app on Xcode 7 (Swift 2) that shows a "Thread 1: signal SIGABRT" running error message in the App Delegate class of my app. However I've actually already got this "Thread 1: signal SIGABRT" running error message in the App Delegate class lots of times, mainly when deleting an outlet reference in my code and forgetting to also delete it from storyboard. But that's certainly the first time I've got this same error when trying to make the command:
let wasteGain = WastesGainsClass(value: enteredMoney, originOrCat: segControlArray[segControl.selectedSegmentIndex], specification: plusEspecTField.text!, date: dateArray, mode: "gain")
gains.append(wasteGain)
NSUserDefaults.standardUserDefaults().setObject(gains, forKey: "gains")
What happens is that if I just comment the line NSUserDefaults.standardUserDefaults().setObject(gains, forKey: "gains") the app doesn't crash! So the error might just be in that line.
If anyone could help me, I`d thank you so much.
PS: WastesGainsClass format is like this:
class WastesGainsClass {
var value:Int = 0
var origin:String
var specification:String
var date:[String]
var mode:String
var rowMode:Int = 0
init(value:Int, originOrCat:String, specification:String, date:[String], mode:String) {
self.value = value
self.origin = originOrCat
self.specification = specification
self.date = date
self.mode = mode
}
}
From documentation:
The NSUserDefaults class provides convenience methods for accessing
common types such as floats, doubles, integers, Booleans, and URLs. A
default object must be a property list, that is, an instance of (or
for collections a combination of instances of): NSData, NSString,
NSNumber, NSDate, NSArray, or NSDictionary. If you want to store any
other type of object, you should typically archive it to create an
instance of NSData.
In Swift you can also use:
Int, UInt, Double, Float and Bool types because they are automatically bridged to NSNumber;
String bridged to NSString
[AnyObject] because it is bridged to NSArray;
[NSObject: AnyObject] because it is bridged to NSDictionary.
Of course type of array elements and dictionary values must be one of above types. Dictionary key type must be NSString (or bridged String).
To store instances of any other class you have two options:
Your custom class must be subclass of NSObject and conform to
NSCoding protocol and then you can archive object of this class to NSData with NSKeyedArchiver.archivedDataWithRootObject() and save it to NSUserDefaults and later retrieve it from NSUserDefaults and unarchive with NSKeyedUnarchiver.unarchiveObjectWithData():
import Foundation
class WastesGainsClass: NSObject, NSCoding {
var value: Int
init(value: Int) {
self.value = value
}
required init(coder aDecoder: NSCoder) {
value = aDecoder.decodeObjectForKey("value") as! Int
}
func encodeWithCoder(aCoder: NSCoder) {
aCoder.encodeObject(value, forKey: "value")
}
}
var gains = [WastesGainsClass(value: 1), WastesGainsClass(value: 2)]
NSUserDefaults.standardUserDefaults().setObject(gains.map { NSKeyedArchiver.archivedDataWithRootObject($0) }, forKey: "gains")
if let gainsData = NSUserDefaults.standardUserDefaults().objectForKey("gains") as? [NSData] {
gains = gainsData.map { NSKeyedUnarchiver.unarchiveObjectWithData($0) as! WastesGainsClass }
}
You can save your custom object properties to dictionary and store that
dictionary in NSUserDefaults:
import Foundation
class WastesGainsClass {
var value: Int
init(value: Int) {
self.value = value
}
}
extension WastesGainsClass {
convenience init(dict: [NSObject: AnyObject]) {
self.init(value: dict["value"] as? Int ?? 0)
}
func toDict() -> [NSObject: AnyObject] {
var d = [NSObject: AnyObject]()
d["value"] = value
return d
}
}
var gains = [WastesGainsClass(value: 1), WastesGainsClass(value: 2)]
NSUserDefaults.standardUserDefaults().setObject(gains.map { $0.toDict() }, forKey: "gains")
if let dicts = NSUserDefaults.standardUserDefaults().objectForKey("gains") as? [[NSObject: AnyObject]] {
gains = dicts.map { WastesGainsClass(dict: $0) }
}
NSUserDefaults unfortunately can't accept arbitrary objects, only objects that can be encoded in a Property List. See Apple's reference guide for Property Lists to learn which objects can be stored.
If you need to save several WastesGainsClass objects, you may wish to write a method that returns a Dictionary encoding their Property List-representable properties, and an initializer that accepts such a Dictionary to restore the object.
However, if you truly need to save multiple custom objects like this, you probably don't want to use NSUserDefaults at all. Consider a document-based app, and look into NSCoding.
The code you posted tries to save an array of custom objects to NSUserDefaults. You can't do that. Implementing the NSCoding methods doesn't help. You can only store things like NSArray, NSDictionary, NSString, NSData, NSNumber, and NSDate in NSUserDefaults.
You need to convert the object to NSData (like you have in some of the code) and store that NSData in NSUserDefaults. You can even store an NSArray of NSData if you need to.
see this post : Attempt to set a non-property-list object as an NSUserDefaults