key-value-observing

I have two classes in my app class A and Class B. Both class A and B are instances of UIViewController. Class A has a button that when pushed pushes class B onto the stack. Class B has a string that class A would like to observe and update it's interface with as needed. I've been able to use: [self addObserver:self forKeyPath:@"name" options:0 context:NULL]; in class B to view the changes to the string. When i try and use the following in class A viewWillAppear method: ClassB *b = [[ClassB alloc]init]; [b addObserver:self forKeyPath:@"name" options:0 context:NULL]; and add the method: (void

I am trying to add header and footer (both of them as UIViews ) but for some reason my footer sticks to the bottom, I'm using the KVO method for watching my content size. I'm presenting here the method where I think the problem is: - (void)updateLayout { // Update the frame of the header view so that it scrolls with the webview content CGRect newHeaderFrame = self.headerView.frame; CGRect newFooterFrame = self.footerView.frame; newHeaderFrame.origin.y = -CGRectGetMinY([self.webView convertRect:self.innerHeaderView.frame toView:self.webView.scrollView]); newFooterFrame.origin.y = self.webView

I am using swift 3.0 running under iOS 10.0 and I want to craft some code that fires when a batch condition is met. for i in 0 ..< rex { async code, disappears and does it stuff } Imagine the async code is a collection of URL requests, that basically background as soon as I loop thru them. Now how can I fire off more code when "rex" requests have completed? I thought of setting up a timer to watch and check every second, but its surely not a good solution. I thought kicking off another thread to simply watch the data being collected, and fire when its quota is full, but well that's worse then

I have a vc with a dynamic var "value" and i need to know when it's changed in a closure in the calling cv. target vc: @objc dynamic var value: String = "" source: if let vc: TagButtonPopupViewController = sb.instantiateController(withIdentifier: NSStoryboard.SceneIdentifier("TagPopupViewController")) as? TagButtonPopupViewController { // configure vc vc.value = sender.title // observe _ = vc.observe(\.value) { (tbvc, change) in print("new string") } // present popup presentViewController(vc, asPopoverRelativeTo: sender.bounds, of: sender, preferredEdge: NSRectEdge.maxY, behavior: NSPopover

I've linked output from the IB to the code, as shown below. class DiaryTableViewCell: UITableViewCell { @IBOutlet weak var TitleLabel: UILabel! @IBOutlet weak var SubTitleLabel: UILabel! @IBOutlet weak var leftImageView: UIImageView! @IBOutlet weak var rightImageView: UIImageView! } Here, I'm registering the class: override func viewDidLoad() { self.title = "My Diary" cellNib = UINib(nibName: "TableViewCells", bundle: nil) tableView.registerClass(DiaryTableViewCell.classForCoder(), forCellReuseIdentifier: kCellIdentifier) } But I keep getting the following runtime error: *** Terminating app

I'm rendering some content in a layer that sits on top of my MKMapView . The whole thing works great with the exception of rotation. When a user rotates the map I need to be able to rotate what I'm rendering in my own layer. The standard answer I found is to use: NSLog(@"heading: %f", self.mapView.camera.heading"); The issue with this is that the content of the heading variable only updates when the pinch/rotate gesture is ending, not during the gesture. I need much more frequent updates. There is no heading property on the mapView itself. I thought maybe using KVO like such: // Somewhere in