I'm trying to make a WatchOS app that can receive images and a title from a iPhone app in SwiftUI.
I create a object that has SecureCoding. The object is called TemplateObject that can have a String and an array of Data.
I convert the images of the iPhone to data and send to Watch as TemplateObject
let data = try! NSKeyedArchiver.archivedData(withRootObject: template, requiringSecureCoding: true)
The image that I was testing has 51kB.
Anyone know what is the problem?
for image transfer to watch always use the WCSession method
- (WCSessionFileTransfer *)transferFile:(NSURL *)file metadata:(nullable NSDictionary<NSString *, id> *)metadata;
we should transfer only a small amount of data through other methods of WCSession
Related
I have a framework that is generating a device UUID once and saving it using UserDefaults. The app has access to the UserDefaults and everything works as expected. However, the framework is not accessing UserDefaults in some cases.
I sorted this out on an iPhone 8 using the synchronize() method:
func getDeviceID() -> String {
if let device = UserDefaults.standard.object(forKey: "DeviceID") as? String {
return device
} else {
let device = UUID().uuidString
UserDefaults.standard.set(device, forKey: "DeviceID")
UserDefaults.standard.synchronize() // this line helped with an iPhone 8
return device
}
}
However, on an older iPhone SE 1st generation the issue comes back.
First, why is this happening at all, and why is the synchronize() method seemingly helping in a newer device? (Both phones are running iOS 13)
Are there any known limitations when accessing UserDefaults from within a framework?
If it is failing when you're reading data right after writing the deviceId to UserDefaults
Then it could be related to how UserDefaults actually stores the data to disk.
The actual write to disk is asynchronous and batched automatically by NSUserDefaults.
Check this
So there's a chance that it is slower for older devices running new iOS versions.
I was trying to pass my swift object from the iOS app to the Watch. However, I found it works for basic types like NSString, but my custom object type.
My custom object is able to cast to NSData
I've made my object implement NSObject and NSCoding, which works well. I can do following without problem:
let encodedChordProgression = NSKeyedArchiver.archivedDataWithRootObject(chordProgressions[1])
let decodedChordProgression = NSKeyedUnarchiver.unarchiveObjectWithData(encodedChordProgression) as! ChordProgression
NSLog("get decodedChordProgression = \(decodedChordProgression.description)")
WatchConnectivity code works for NSString
In iPhone:
try WatchSessionManager.sharedManager.updateApplicationContext(["data": "mystringishere"])
with Watch:
dispatch_async(dispatch_get_main_queue()) { [weak self] in
self?.dataSourceChangedDelegates.forEach { $0.dataSourceDidUpdate(applicationContext["data"] as! NSString)}
}
works.
My custom object with WatchConnectivity Failed
However, when I switch the object to my own object, it failed by not calling the dataSourceChangedDelegates callback function. That is:
In iPhone:
let encodedChordProgression = NSKeyedArchiver.archivedDataWithRootObject(chordProgressions[1])
try WatchSessionManager.sharedManager.updateApplicationContext(["data": encodedChordProgression])
with Watch:
dispatch_async(dispatch_get_main_queue()) { [weak self] in
self?.dataSourceChangedDelegates.forEach { $0.dataSourceDidUpdate(applicationContext["data"] as! NSData)}
}
and
func dataSourceDidUpdate(encodedChordProgression: NSData) {
let chordProgression = NSKeyedUnarchiver.unarchiveObjectWithData(encodedChordProgression) as! ChordProgression
NSLog("get something here: \(chordProgression.description)")
}
What I've tried & my problem
I've tried to read the system.log of both the iPhone app and Watch app, but I couldn't find any clue, which is the biggest problem I have now.
The full code is: here (checkout 7f2a72c6004f6580e2a38a2d7fd0ed2cef8a2b2e)
NSKeyedArchiver/NSKeyedUnarchiver won't work in this way unfortunately. This is because even though you may share class files between your watchkit and iOS targets, they are essentially different classes to the compiler because they are compiled for different architectures.
What I have done to get around this issue myself (because I initially tried to do the same thing) is serialize my custom objects to a json dictionary (or json NSData if you like) and send that. Here is a github project I have made that automatically serializes your swift objects to json for you (specifically with this use case in mind).
I tried with "NSKeyedArchiver/NSKeyedUnarchiver" and this is working perfectly.
no need to go for serialization and all.
your dictionary should have same type of data and Archiver is doing it very well.
The following is a test method for communicating between the watchOS and iOS components of my app:
- (void)session:(WCSession *)session didReceiveMessage:(NSDictionary<NSString *,id> *)message replyHandler:(void (^)(NSDictionary<NSString *,id> * _Nonnull))replyHandler {
NSArray *responseArray = #[#"hello", "world"];
NSDictionary *responseDict = #{#"response": responseArray};
replyHandler(response);
}
This works perfectly - in the reply handler on the watch I can log the contents of responseDict and see the objects #"hello" and #"world". However, if I change responseArray to contain NSManagedObject instances (for sending actual data to the watch), the sendMessage error handler is triggered with an error saying Payload could not be delivered. Before I change my database structure to include a uuid for the entities I need to send (so I can send them represented by their UUID in NSString format), I just wanted to check: is it actually possible to send NSManagedObject instances to watchOS?
No, it's not possible to send NSManagedObject instances between contexts, threads, or devices.
A managed object only exists within its managed object context. Its data would be nil, if you tried to access or copy it outside its context.
If your Core Data persistent store is on the phone, but you want to display a managed object's data on the watch, you'd first to move the data from the managed object into another type (e.g., a dictionary), and then send that data to the watch.
See this answer for more details.
I have an iPhone (iOS 8) and Apple Watch (watchOS 1) apps that share their data using Core Data (SQLite store, placed in shared app group). Both apps are using the same data access code that is placed in shared framework. NSPersistentStoreCoordinator is being set up in the following way:
lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator = {
let sharedContainerURL = NSFileManager.defaultManager().containerURLForSecurityApplicationGroupIdentifier(self.sharedAppGroup)!
let storeURL = sharedContainerURL.URLByAppendingPathComponent(self.databaseName)
let coordinator = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel)
var error: NSError? = nil
if coordinator.addPersistentStoreWithType(NSSQLiteStoreType, configuration: nil, URL: storeURL, options: nil, error: &error) == nil {
fatalError("Unable to add persistent store: \(error)")
}
return coordinator
}()
From my understanding, in runtime each app has its own NSPersistenStoreCoordinator instance (as iPhone apps and WatchKit extensions do have completely separate address space), but these two connect to exactly the same SQLite database file.
How can an iPhone app be notified when Watch app changes some data in the common SQLite store and the other way around: how can a Watch app be notified when the iPhone app changes some data in the common persistent store?
The solution that I've found quite satisfactory was to use MMWormhole library.
It works by using CFNotificationCenter Darwin Notifications and writing/reading data files in the shared app group, which results in instant communication between an iOS app and an app extension (Watch app, today's widget, etc).
Basic code goes like this:
Wormhole initialization
wormhole = MMWormhole(applicationGroupIdentifier: appGroup, optionalDirectory: nil)
Passing data object to a wormhole
let payload = ["Key": "Value"]
wormhole.passMessageObject(payload, identifier: theSameMessageIdentifier)
Listening for incoming object from a wormhole
wormhole.listenForMessageWithIdentifier(theSameMessageIdentifier) { message -> Void in
if let payloadDictionary = message as? Dictionary<String, String> {
// Do some work
}
}
It's as simple as that.
Not easily. There is no way to send a direct communication between the two applications.
My current recommendation in this regard is to use files on disk that include the objectIDs of anything that has changed from one app to the other.
When you detect a save to disk you write a file that, for example, is JSON and includes up to three arrays: update, insert, delete. The file name should be some form of timestamp.
Separately you should be watching the directory for any files created by the other app and consume them. Load the ObjectIDs and then create a notification out of the ala iCloud or in iOS 9 a remote notification. Then delete the file after process.
On launch, remove all files from the other store since you will automatically be aware of anything that happened pre-launch.
Not simple but fairly straight forward.
Just trying to update some Core Data apps with Continuity and have run into a bit of an issue with using the selected objects ID in the userInfo dictionary to display the correct data on the continuing device.
My first thought was to use the ObjectID, however on the receiving device this would never find a corresponding object in the Core Data store.
As it turns out the URL representation of the objectID contains the UUID of the store itself, and because the two stores UUID's are different this is obviously going to fail.
So I guess I could replace the Core Data store's UUID in the URL with the continuing devices UUID and use this, and no doubt it would work.
The Url seems to be of the following format
Does anyone know what the correct way would be to pass a reference to an object between two devices with core data stores that are synchronised via iCloud?
I'll answer this one myself and see if there are any better answers...
I pass the url of the objectID (from objectID.URIRepresentation) using Continuity API and on the receiving device create a new URL using the following:
url is the url passed in the NSUserActivity.userInfo dictionary
let storeUUID = self.identifierForStore()
// Switch the host component to be the local storeUUID
let newURL = NSURL(scheme: url.scheme!, host: storeUUID, path: url.path!)
func identifierForStore()->NSString? {
if let store = self.persistentStoreCoordinator?.persistentStores[0] as? NSPersistentStore {
return store.identifier
} else {
return nil
}
}
This seems to work just fine - hope it helps someone