I'm writing a Swift app for iOS. I need to set and later retrieve a UIColor object to NSUserDefaults.
I set it like this:
var userSelectedColor : NSData? = (NSUserDefaults.standardUserDefaults().objectForKey("UserSelectedColor") as? NSData)
if (userSelectedColor == nil) {
var colorToSetAsDefault : UIColor = UIColor.redColor()
var data : NSData = NSKeyedArchiver.archivedDataWithRootObject(colorToSetAsDefault)
NSUserDefaults.standardUserDefaults().setObject(data, forKey: "UserSelectedColor")
NSUserDefaults.standardUserDefaults().synchronize()
println("SET DEFAULT USER COLOR TO RED")
}
But I can't seem to get it back because the unarchive method on NSKeyedArchiver seems to be missing in Swift.
var userSelectedColorData: NSData? = (NSUserDefaults.standardUserDefaults().objectForKey("UserSelectedColor") as NSData)
var userSelectedColor : UIColor? = NSKeyedArchiver.unarchiveObjectWithData(userSelectedColorData)
What is the proper way to do this in Swift / iOS 8?
Unarchiving is done with NSKeyedUnarchiver, not with NSKeyedArchiver. You also should
use conditional casts (as?) to ensure that the application does not crash if the
saved user default is not of the expected type:
if let userSelectedColorData = NSUserDefaults.standardUserDefaults().objectForKey("UserSelectedColor") as? NSData {
if let userSelectedColor = NSKeyedUnarchiver.unarchiveObjectWithData(userSelectedColorData) as? UIColor {
println(userSelectedColor)
}
}
Related
Saving NSMutableArray with NSUserDefaults in Swift Returns Nil
setObject method removed my codes like that and not work. i try all set types still not work. Any idead ?
var banksAccount : NSMutableArray = []
for bankJson in (self.users?[0].Banks)! {
self.banksAccount.add(bankJson)
}
UserDefaults.standard.set(self.banksAccount, forKey: "myBanksAccounts")
UserDefaults.standard.synchronize()
For saving
let cacheArrayData = NSKeyedArchiver.archivedData(withRootObject: banksAccount)
UserDefaults.standard.set(cacheArrayData, forKey: "EventItems")
For retrieving
let retriveArrayData = UserDefaults.standard.object(forKey: "EventItems") as? NSData
let retriveArray = NSKeyedUnarchiver.unarchiveObject(with: retriveArrayData! as Data) as? NSArray
self.eventsArray = NSMutableArray(array:retriveArray!)
Using swift 3.0, I'm trying to add an array of objects into user defaults. As this isn't one of the regular UserDefault types I've realised that the object or array of objects (can't work out which one) will need to be parsed to the type NSData to then be added to UserDefaults.
My attempt so far is the following:
Within the object
func updateDefaults()
{
let data = NSData(data: MyVariables.arrayList)
UserDefaults.standard.set(data, forKey: "ArrayList")
}
Where MyVariables.arrayList is the array of objects.
Lastly, if possible it would be nice to know how to retrieve this from UserDefaults and convert it to the original one-dimensional array of objects.
Thanks
REPOSITORY: https://github.com/Clisbo/ModularProject
You can't save your custom array in NSUserDefaults. To do that you should change them to NSData then save it in NSUserDefaults Here is the code.
var custemArray: [yourArrayType] {
get {
if let data = NSUserDefaults.standardUserDefaults().objectForKey("yourKey") as? NSData {
let myItem = NSKeyedUnarchiver.unarchiveObjectWithData(data) as? yourType
}
}
set {
let data =NSKeyedArchiver.archivedDataWithRootObject(yourObject);
NSUserDefaults.standardUserDefaults().setObject(data, forKey: "yourKey")
NSUserDefaults.standardUserDefaults().synchronize()
}
}
I am having difficulty figuring out how to get an NSData representation of an image from a CGImageRef. All of the answers I've found make use of UIImage or NSImage, but my application is cross-platform, so I want to use only Core Graphics. Objective-C answers state simply that CFData is toll-free bridged to NSData and simply cast it, but Swift will not allow this. The closest I've got is:
var image: CGImageRef? = nil
//...
if let dataProvider: CGDataProviderRef = CGDataProviderCreateWithURL(url) {
image = CGImageCreateWithPNGDataProvider(dataProvider, nil, false, CGColorRenderingIntent.RenderingIntentDefault)
// works fine
//...
if let data = CGDataProviderCopyData(CGImageGetDataProvider(image)) as? NSData {
// Do something with data, if only it ever got here!
}
}
but the cast doesn't ever succeed...
CGDataProviderCopyData() returns the optional CFData?, and that cannot be cast to the non-optional NSData. But you can convert/bridge
it to NSData? and use that in the optional binding:
if let data = CGDataProviderCopyData(CGImageGetDataProvider(image)) as NSData? {
// Do something with data ...
}
Here is a simpler example demonstrating the same issue with
CFString and NSString:
let cfstr : CFString? = "Hello world"
if let nsstr = cfstr as? NSString {
print("foo") // not printed
}
if let nsstr = cfstr as NSString? {
print("bar") // printed
}
But I admit that my explanation is not fully satisfying, because
a similar optional cast works in other cases:
class MyClass { }
class MySubclass : MyClass { }
let mc : MyClass? = MySubclass()
if let msc = mc as? MySubclass {
print("yes") // printed
}
So this must be related to the toll-free bridging between CoreFoundation
and Foundation types.
Good morning all, I am using Swift "new for me" and core data I am trying to fetch my stored UIIMage from core data the following way. FYI it is saved as Binary Data in core. And I can see the data if I NSLog it. My Fetch Request looks like this. I have NO ERRORS but my image is not showing.
When I save to Core Data the NSLog looks like this..
Did I get to Save Image
2015-10-12 09:05:43.307 Car-Doc-Safe-Plus[13972:3524049] The NewImage has this in it (entity: Documents; id: 0x7fd4c0432060 ; data: {
autoClub = nil;
driverLicense = <89504e47 0d0a1a0a 0000000d 49484452 00000215 00000155 08020000 00d7368a d8000000 01735247 4200aece 1ce90000 001c>;
insuranceID = nil;
noteText = nil;
plate = nil;
registration = nil;
})
But when i Fetch it looks like this..
The Request has this in it (entity: Documents; predicate: ((null)); sortDescriptors: ((null)); type: NSManagedObjectResultType; )
**override func viewDidLoad() {
super.viewDidLoad()
let appDel:AppDelegate = (UIApplication.sharedApplication().delegate as! AppDelegate)
let context:NSManagedObjectContext = appDel.managedObjectContext!
let request = NSFetchRequest(entityName: "Documents")
request.returnsObjectsAsFaults = false;
let results : NSArray
try! results = context.executeFetchRequest(request)
if results.count > 0 {
let res = results[0] as! NSManagedObject
carImageView.image = res.valueForKey("driverLicense")as? UIImage
}
}**
I know I am missing something but I cannot figure it out. Any help is greatly appreciated.
JZ
The "binary data" type in Core Data is intended for reading and writing NSData objects. Since you want to read/write UIImage, you need to use the "transformable" type. With transformable, Core Data will attempt to use NSCoding to encode/decode the data, converting it to/from NSData as needed (Swift as? will not do this). Since UIImage conforms to NSCoding, you don't need to do any extra work except to tell Core Data to convert the data.
OK, this is a case I came across when working with CGImageSource and noticed that the toll-free-bridging between CFDictionary and NSDictionary seems to run into problems in certain cases. I've managed to construct the below example to show what I mean:
func optionalProblemDictionary() -> CFDictionary? {
let key = "key"
let value = "value"
var keyCallBacks = CFDictionaryKeyCallBacks()
var valueCallBacks = CFDictionaryValueCallBacks()
let cfDictionary = CFDictionaryCreate(kCFAllocatorDefault, UnsafeMutablePointer(unsafeAddressOf(key)), UnsafeMutablePointer(unsafeAddressOf(value)), 1, &keyCallBacks, &valueCallBacks)
return cfDictionary
}
Fairly straightforward (and a bit silly) but its a function returning and optional CFDictionary. The "fun" starts when trying to create an NSDictionary from this function:
Why won't the following work?
if let problemDictionary = optionalProblemDictionary() as? NSDictionary {
print(problemDictionary) // never enters, no warnings, compiles just fine
}
While this works fine?
if let cfDictionary = optionalProblemDictionary() {
let problemDictionary = cfDictionary as NSDictionary
print(problemDictionary)
}
XCode 7.0 (7A220)
The reason seems to be that the function returns an optional
CFDictionary? and that can not be cast to a (non-optional)
NSDictionary.
Here is a simpler example demonstrating the same problem with CFString vs NSString:
let cfString = "foobar" as CFString?
if let s1 = cfString as? NSString {
print("s1 = \(s1)") // not executed
}
(The question remains why this does not give a compiler error or
at least a compiler warning because this optional cast can
never succeed.)
But a casting to an optional NSString? works:
if let s2 = cfString as NSString? {
print("s2 = \(s2)") // prints "s2 = foobar"
}
In your case, if you change the "problematic case" to
if let problemDictionary = cfDict as NSDictionary? {
print(problemDictionary)
}
then the if-block is executed.
Note that your method to build a CFDictionary in Swift is not correct
and actually caused program crashes in my test. One reason is that
the dictionary callbacks are set to empty structures.
Another problem is that unsafeAddressOf(key) bridges the Swift
string to an NSString which can be deallocated immediately.
I don't know what the best method is to build a CFDictionary in Swift,
but this worked in my test:
func optionalProblemDictionary() -> CFDictionary? {
let key = "key" as NSString
let value = "value" as NSString
var keys = [ unsafeAddressOf(key) ]
var values = [ unsafeAddressOf(value) ]
var keyCallBacks = kCFTypeDictionaryKeyCallBacks
var valueCallBacks = kCFTypeDictionaryValueCallBacks
let cfDictionary = CFDictionaryCreate(kCFAllocatorDefault, &keys, &values, 1, &keyCallBacks, &valueCallBacks)
return cfDictionary
}