I'm populating a List with a Realm Result set.
When navigating from this list it opens a new view then automatically closes that view.
Using a struct presents no issue.
Why would the second view automatically close?
I have a screen recording but cant post here.
import SwiftUI
import Combine
struct TestStruct:Identifiable{
let id = UUID()
let firstname: String
}
extension TestStruct {
static func all() -> [TestStruct]{
return[
TestStruct(firstname: "Joe"),
TestStruct(firstname: "Jane"),
TestStruct(firstname: "Johns")
]
}
}
struct TestListView: View {
let realmList = Horoscope.getHoroscopes() //Fetches from Realm
let structList = TestStruct.all()
var body: some View {
NavigationView{
// This owrks
// List(structList) { item in
// MyItemRow(itemTxt: item.firstname)
// }
//This automatically closes the view
List(realmList) { item in
MyItemRow(itemTxt: item.firstname)
}
.navigationBarTitle("Charts", displayMode: .automatic)
.navigationBarItems(trailing: EditButton())
}
}
}
struct MyItemRow: View {
var itemTxt:String
var body: some View {
NavigationLink(destination: Text("Test")) {
Text(itemTxt)
}
}
}
struct TestListView_Previews: PreviewProvider {
static var previews: some View {
TestListView()
}
}
I think the answer can be found here
In short, do not generate the id of the collection on which the ForEach iterates. It would detect a change and navigate back.
Realm object has an auto generated id property with each reference, try replacing it with a consistent id
The following solution worked for me.
The code with an issue (specifying id: \.self is the root cause since it uses the hash calculated from all objects the Stream object consists of, including the data that lies in a subarray).
...
List(streams, id: \.self) { stream in
...
The code with no issues:
...
List(streams, id: \._id) { stream in
// or even List(streams) { stream in
...
The streams is a #ObservedResults(Stream.self) var streams and the object scheme is:
final class Stream: Object, ObjectKeyIdentifiable {
#Persisted(primaryKey: true) var _id: ObjectId
#Persisted var title: String
#Persisted var subtitle: String?
#Persisted var topics = RealmSwift.List<Topic>()
// tags, etc.
}
The issue happened when I added new topic at the topics list in the first stack of the navigationView.
I keep receiving this error, CFNetwork SSLHandshake failed (-9807), in the debug window and have no data displayed when trying to populate a UITableViewController with Firebase data. I have tried this potential solution iOS 9 ATS and Firebase REST but still have the issue.
The code I am using is (Credit to #DavidEast)
class TableViewController1: UITableViewController {
// your firebase reference as a property
var ref: Firebase!
// your data source, you can replace this with your own model if you wish
var items = [FDataSnapshot]()
override func viewDidLoad() {
super.viewDidLoad()
// initialize the ref in viewDidLoad
ref = Firebase(url:"https://the-lighthouse-app.firebase.io/states")
}
override func viewDidAppear(animated: Bool) {
super.viewDidAppear(animated)
// listen for update with the .Value event
ref.observeEventType(.Value) { (snapshot: FDataSnapshot!) in
var newItems = [FDataSnapshot]()
// loop through the children and append them to the new array
for item in snapshot.children {
newItems.append(item as! FDataSnapshot)
}
// replace the old array
self.items = newItems
// reload the UITableView
self.tableView.reloadData()
}
}
}
Im new to realm. I have read the documentation and followed the examples in creating and querying the database. Whenever I run the code below it crashes on the line
let realm = Realm
I have a view controller that I am trying to query realm like so:
// Get the default Realm
let realm = Realm()
// Query using an NSPredicate
let predicate = NSPredicate(format: "s3_url = %#", s3_url)
let medias = realm.objects(MediaRealm).filter(predicate)
everytime i run this i get Thread1: EXC_BAD_ACCESS
let realm = Realm()
import UIKit
import Alamofire
import RealmSwift
class ViewController: UIViewController {
let mediaCollection = MediaCollection()
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
loadInitialData()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func loadInitialData(){
//connect to url
mediaCollection.fetch(onSuccess:{ self.onEventFetched($0) }, onError:{ self.displayAlert($0)})
}
func onEventFetched()->Void{
println("Got stuff")
println(mediaCollection.models.count)
processCollection()
}
func processCollection()->Void{
for media in mediaCollection.models{
let m = media as! Media
println(m.s3_url)
println(m.title)
if let s3_url = m.s3_url{
//query database, if it already exists dont download it
// Get the default Realm
let realm = Realm()
// Query using an NSPredicate
let predicate = NSPredicate(format: "s3_url = %#", s3_url)
let medias = realm.objects(MediaRealm).filter(predicate)
if medias.count == 0 {
println("no files found")
//downloadFile(s3_url)
}
}
}
}
What am I doing wrong?
This was caused by me adding new fields to the database and not running a migration.
Solution was to delete the app and start over.
I am trying to use Swift to implement the Microsoft Band SDK. I keep getting this error when trying to set up my code.
class ViewController: UIViewController, UITableViewDelegate, UIImagePickerControllerDelegate, UINavigationControllerDelegate, MSBClientManagerDelegate, UIScrollViewDelegate {
I have never seen this before, but I have also never tried to convert an Objective C sample to Swift.
Any help would be appreciated!
EDIT: Here is the protocol from Objective C
#protocol MSBClientManagerDelegate<NSObject>
- (void)clientManager:(MSBClientManager *)clientManager clientDidConnect:(MSBClient *)client;
- (void)clientManager:(MSBClientManager *)clientManager clientDidDisconnect:(MSBClient *)client;
- (void)clientManager:(MSBClientManager *)clientManager client:(MSBClient *)client didFailToConnectWithError:(NSError *)error;
#end
EDIT 2: After using suggested Swift Helper class
This is how I am trying to set up the connection.
var clients:NSArray = bandHelper.attachedClients()!
var firstClient: MSBClient = clients[0] as MSBClient
if (clients.count == 0){
println("The band is not detected")
return
}
I have no clue how this should be set up
bandHelper.connectClient(firstClient, {completion: (connected:true -> void in)})
println("Please wait...connecting to band")
Then, when trying to send a photo to the band, this function does not work
bandHelper.client?.personalizationManager.updateMeTileImage(bandScaledImage, { (completionHandler: NSError!) -> Void in
NSLog("%#", NSError())})
I am getting thrown off by using the helper class. Any help would be appreciated!
Sample Project
I linked a sample Swift project for Microsoft Band Kit iOS that can send a haptic to the band. Find the link here: http://droolfactory.blogspot.com/2015/03/ios-swift-example-of-connecting-with.html
Microsoft Band Bridging Header
First to convert the Objective-C classes to be used with Swift, create a Bridging Header. Mine look like this for just the MicrosoftBandKit-iOS framework:
#ifndef ModuleName_Bridging_Header_h
#define ModuleName_Bridging_Header_h
#import <MicrosoftBandKit_iOS/MicrosoftBandKit_iOS.h>
#endif
Make sure to replace the ModuleName with the name of your apps Module. Find more on Bridging Header files at: https://developer.apple.com/library/ios/documentation/Swift/Conceptual/BuildingCocoaApps/MixandMatch.html
Band Helper Class
Next I wrapped the MSBClientManagerDelegate in a helper class (BandManager) which uses a singleton to manage the Band. I have a gist for it here (https://gist.github.com/mthistle/8f6eb30c68a918fc6240)
The code for this the gist is:
import Foundation
let kConnectionChangedNotification = "kConnectionChangedNotification"
let kConnectionFailedNotification = "kConnectionFailedNotification"
private let _SharedBandManagerInstance = BandManager()
class BandManager : NSObject, MSBClientManagerDelegate {
private(set) var client: MSBClient?
private var connectionBlock: ((Bool) -> ())?
private var discoveredClients = [MSBClient]()
private var clientManager = MSBClientManager.sharedManager()
class var sharedInstance: BandManager {
return _SharedBandManagerInstance
}
override init() {
super.init()
self.clientManager.delegate = self
}
func attachedClients() -> [MSBClient]? {
if let manager = self.clientManager {
self.discoveredClients = [MSBClient]()
for client in manager.attachedClients() {
self.discoveredClients.append(client as! MSBClient)
}
}
return self.discoveredClients
}
func disconnectClient(client: MSBClient) {
if (!client.isDeviceConnected) {
return;
}
if let manager = self.clientManager {
manager.cancelClientConnection(client)
self.client = nil
}
}
func connectClient(client: MSBClient, completion: (connected: Bool) -> Void) {
if (client.isDeviceConnected && self.client == client) {
if (self.connectionBlock != nil)
{
self.connectionBlock!(true)
}
return;
}
if let connectedClient = self.client {
self.disconnectClient(client)
}
self.connectionBlock = completion;
self.clientManager.connectClient(client)
}
func clientManager(clientManager: MSBClientManager!, clientDidConnect client: MSBClient!) {
if (self.connectionBlock != nil) {
self.client = client
self.connectionBlock!(true)
self.connectionBlock = nil
}
self.fireClientChangeNotification(client)
}
func clientManager(clientManager: MSBClientManager!, clientDidDisconnect client: MSBClient!) {
self.fireClientChangeNotification(client)
}
func clientManager(clientManager: MSBClientManager!, client: MSBClient!, didFailToConnectWithError error: NSError!) {
if error != nil {
println(error)
}
NSNotificationCenter.defaultCenter().postNotificationName(kConnectionFailedNotification, object: self, userInfo: ["client": client])
}
func fireClientChangeNotification(client: MSBClient) {
NSNotificationCenter.defaultCenter().postNotificationName(kConnectionChangedNotification, object: self, userInfo: ["client": client])
}
}
In Objective-C, I would normally use something like this:
static NSString *kViewTransformChanged = #"view transform changed";
// or
static const void *kViewTransformChanged = &kViewTransformChanged;
[clearContentView addObserver:self
forKeyPath:#"transform"
options:NSKeyValueObservingOptionNew
context:&kViewTransformChanged];
I have two overloaded methods to choose from to add an observer for KVO with the only difference being the context argument:
clearContentView.addObserver(observer: NSObject?, forKeyPath: String?, options: NSKeyValueObservingOptions, context: CMutableVoidPointer)
clearContentView.addObserver(observer: NSObject?, forKeyPath: String?, options: NSKeyValueObservingOptions, kvoContext: KVOContext)
With Swift not using pointers, I'm not sure how to dereference a pointer to use the first method.
If I create my own KVOContext constant for use with the second method, I wind up with it asking for this:
let test:KVOContext = KVOContext.fromVoidContext(context: CMutableVoidPointer)
EDIT: What is the difference between CMutableVoidPointer and KVOContext? Can someone give me an example how how to use them both and when I would use one over the other?
EDIT #2: A dev at Apple just posted this to the forums: KVOContext is going away; using a global reference as your context is the way to go right now.
There is now a technique officially recommended in the documentation, which is to create a private mutable variable and use its address as the context.
(Updated for Swift 3 on 2017-01-09)
// Set up non-zero-sized storage. We don't intend to mutate this variable,
// but it needs to be `var` so we can pass its address in as UnsafeMutablePointer.
private static var myContext = 0
// NOTE: `static` is not necessary if you want it to be a global variable
observee.addObserver(self, forKeyPath: …, options: [], context: &MyClass.myContext)
override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey: Any]?, context: UnsafeMutableRawPointer?) {
if context == &myContext {
…
}
else {
super.observeValue(forKeyPath: keyPath, of: object, change: change, context: context)
}
}
Now that KVOContext is gone in Xcode 6 beta 3, you can do the following. Define a global (i.e. not a class property) like so:
let myContext = UnsafePointer<()>()
Add an observer:
observee.addObserver(observer, forKeyPath: …, options: nil, context: myContext)
In the observer:
override func observeValueForKeyPath(keyPath: String!, ofObject object: AnyObject!, change: [NSObject : AnyObject]!, context: UnsafePointer<()>) {
if context == myContext {
…
} else {
super.observeValueForKeyPath(keyPath, ofObject: object, change: change, context: context)
}
}
Swift 4 - observing contentSize change on UITableViewController popover to fix incorrect size
I had been searching for an answer to change to a block based KVO because I was getting a swiftlint warning and it took me piecing quite a few different answers together to get to the right solution. Swiftlint warning:
Block Based KVO Violation: Prefer the new block based KVO API with keypaths when using Swift 3.2 or later. (block_based_kvo).
My use case was to present a popover controller attached to a button in a Nav bar in a view controller and then resize the popover once it's showing - otherwise it would be too big and not fitting the contents of the popover. The popover itself was a UITableViewController that contained static cells, and it was displayed via a Storyboard segue with style popover.
To setup the block based observer, you need the following code inside your popover UITableViewController:
// class level variable to store the statusObserver
private var statusObserver: NSKeyValueObservation?
// Create the observer inside viewWillAppear
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
statusObserver = tableView.observe(\UITableView.contentSize,
changeHandler: { [ weak self ] (theTableView, _) in self?.popoverPresentationController?.presentedViewController.preferredContentSize = theTableView.contentSize
})
}
// Don't forget to remove the observer when the popover is dismissed.
override func viewDidDisappear(_ animated: Bool) {
if let observer = statusObserver {
observer.invalidate()
statusObserver = nil
}
super.viewDidDisappear(animated)
}
I didn't need the previous value when the observer was triggered, so left out the options: [.new, .old] when creating the observer.
Update for Swift 4
Context is not required for block-based observer function and existing #keyPath() syntax is replaced with smart keypath to achieve swift type safety.
class EventOvserverDemo {
var statusObserver:NSKeyValueObservation?
var objectToObserve:UIView?
func registerAddObserver() -> Void {
statusObserver = objectToObserve?.observe(\UIView.tag, options: [.new, .old], changeHandler: {[weak self] (player, change) in
if let tag = change.newValue {
// observed changed value and do the task here on change.
}
})
}
func unregisterObserver() -> Void {
if let sObserver = statusObserver {
sObserver.invalidate()
statusObserver = nil
}
}
}
Complete example using Swift:
//
// AppDelegate.swift
// Photos-MediaFramework-swift
//
// Created by Phurg on 11/11/16.
//
// Displays URLs for all photos in Photos Library
//
// #see http://stackoverflow.com/questions/30144547/programmatic-access-to-the-photos-library-on-mac-os-x-photokit-photos-framewo
//
import Cocoa
import MediaLibrary
// For KVO: https://developer.apple.com/library/content/documentation/Swift/Conceptual/BuildingCocoaApps/AdoptingCocoaDesignPatterns.html#//apple_ref/doc/uid/TP40014216-CH7-ID12
private var mediaLibraryLoaded = 1
private var rootMediaGroupLoaded = 2
private var mediaObjectsLoaded = 3
#NSApplicationMain
class AppDelegate: NSObject, NSApplicationDelegate {
#IBOutlet weak var window: NSWindow!
var mediaLibrary : MLMediaLibrary!
var allPhotosAlbum : MLMediaGroup!
func applicationDidFinishLaunching(_ aNotification: Notification) {
NSLog("applicationDidFinishLaunching:");
let options:[String:Any] = [
MLMediaLoadSourceTypesKey: MLMediaSourceType.image.rawValue, // Can't be Swift enum
MLMediaLoadIncludeSourcesKey: [MLMediaSourcePhotosIdentifier], // Array
]
self.mediaLibrary = MLMediaLibrary(options:options)
NSLog("applicationDidFinishLaunching: mediaLibrary=%#", self.mediaLibrary);
self.mediaLibrary.addObserver(self, forKeyPath:"mediaSources", options:[], context:&mediaLibraryLoaded)
NSLog("applicationDidFinishLaunching: added mediaSources observer");
// Force load
self.mediaLibrary.mediaSources?[MLMediaSourcePhotosIdentifier]
NSLog("applicationDidFinishLaunching: done");
}
override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
NSLog("observeValue: keyPath=%#", keyPath!)
let mediaSource:MLMediaSource = self.mediaLibrary.mediaSources![MLMediaSourcePhotosIdentifier]!
if (context == &mediaLibraryLoaded) {
NSLog("observeValue: mediaLibraryLoaded")
mediaSource.addObserver(self, forKeyPath:"rootMediaGroup", options:[], context:&rootMediaGroupLoaded)
// Force load
mediaSource.rootMediaGroup
} else if (context == &rootMediaGroupLoaded) {
NSLog("observeValue: rootMediaGroupLoaded")
let albums:MLMediaGroup = mediaSource.mediaGroup(forIdentifier:"TopLevelAlbums")!
for album in albums.childGroups! {
let albumIdentifier:String = album.attributes["identifier"] as! String
if (albumIdentifier == "allPhotosAlbum") {
self.allPhotosAlbum = album
album.addObserver(self, forKeyPath:"mediaObjects", options:[], context:&mediaObjectsLoaded)
// Force load
album.mediaObjects
}
}
} else if (context == &mediaObjectsLoaded) {
NSLog("observeValue: mediaObjectsLoaded")
let mediaObjects:[MLMediaObject] = self.allPhotosAlbum.mediaObjects!
for mediaObject in mediaObjects {
let url:URL? = mediaObject.url
// URL does not extend NSObject, so can't be passed to NSLog; use string interpolation
NSLog("%#", "\(url)")
}
}
}
}