I have just added a UISwitch within a cell in my settings menu and I am having issues with the switches state being reverted to on when I leave the view.
I have tried adding this code:
override func viewDidAppear(animated: Bool) {
if autoAdjust == true {
dupSwitch.on = true
} else {
dupSwitch.on = false
}
}
While this does work, it isn't ideal as there is an obvious jump between states when the view appears.
How can I ensure that the switch stays in whatever position the user left it in when they leave the view?
How can I ensure that the switch stays in whatever position the user left it in when they leave the view?
Store the current state of the switch in the model class (in the Model-View-Controller sense). The value of the autoAdjust variable should be saved in an object that does not get unloaded with the view - i.e. in your model class.
When the view is about to appear, read the current state of the switch, and set dupSwitch.on to the state stored in the model.
Note: To avoid showing the process of switching, move your logic from viewDidAppear to viewWillAppear. Your code can be simplified, too - you do not need a conditional:
override func viewWillAppear(animated: Bool) {
dupSwitch.on = autoAdjust
}
Related
I am controlling an NSSwitch state in a function. I declared trigger1ToggleOut outlet earlier, when I trigger the function the switch turns on, but it happens instantly, without the sliding animation.
Is there a way to make it animate? (like you can do with progress indicators)
func turnSwitchOn()
{
trigger1ToggleOut.state = .on
}
Any help would be great.
Adding my comment as answer, Quoting from apple doc
The values off and on indicate that the switch is in the off or on
position. The switch treats any value other than off as on. Setting
this property through the animator() proxy animates the switch to the
new value.
So you can change your turnSwitchOn method to use animator() proxy as shown below
func turnSwitchOn() {
trigger1ToggleOut.animator().state = .on
}
Here is the O/P
You can declare switch as -
var mySwitch = UISwitch()
Setting the switch on
mySwitch.setOn(true, animated: true)
For turning it off
mySwitch.setOn(false, animated: true)
This will animate while changing the state.
I have a custom control. If it inherits from NSView, it automatically becomes the first responder when I click on it. If it inherits from NSControl, it does not. This difference in behavior persists, even if I override mouseDown(with:) and don't call super.
Code:
class MyControl: NSView {
override var canBecomeKeyView: Bool { return true }
override var acceptsFirstResponder: Bool { return true }
override func drawFocusRingMask() { bounds.fill() }
override var focusRingMaskBounds: NSRect { return bounds }
override func draw(_ dirtyRect: NSRect) {
NSColor.white.set()
bounds.fill()
}
}
As you can see, I override acceptsFirstResponder among other methods and properties that are key view and responder related. I have also checked the refusesFirstResponder property. It is set to false.
What is the reason for this difference in behavior?
Is there a method or property that I can override to influence it?
Say I want the behavior where the view becomes the first responder when clicked and the view inherits from NSControl, is calling window!.makeFirstResponder(self) at the beginning of my mouse-down event handler a good solution or is there a better one?
The property to override is needsPanelToBecomeKey.
A Boolean value indicating whether the view needs its panel to become the key window before it can handle keyboard input and navigation.
The default value of this property is false. Subclasses can override this property and use their implementation to determine if the view requires its panel to become the key window so that it can handle keyboard input and navigation. Such a subclass should also override acceptsFirstResponder to return true.
This property is also used in keyboard navigation. It determines if a mouse click should give focus to a view—that is, make it the first responder). Some views (for example, text fields) want to receive the keyboard focus when you click in them. Other views (for example, buttons) receive focus only when you tab to them. You wouldn't want focus to shift from a textfield that has editing in progress simply because you clicked on a check box.
NSView returns true, NSControl returns false.
I'm trying to observe a change to the selection of an NSPopUpButton in Swift 4. In my view controller's viewDidLoad() I've set up the observation token to observe the selectedItem property of the NSPopUpButton
override func viewDidLoad() {
super.viewDidLoad()
observation = observe(\.myPopUpButton.selectedItem) {
objectToObserve, change in
if change.kind == NSKeyValueObservedChange.Kind.setting {
// code to execute goes here
}
}
I set a breakpoint on the line where observation is set to determine that the token is being configured with the correct key path. I also set a break inside the closure to see when it is executed. When I change the selection of the NSPopUpButton, the closure does not execute.
selectedItem is of type, NSMenuItem?, so my suspicion is that I can't set an observation on an optional property. But I can't find anything in Apple's documentation that states whether or not that is the case and I'm not sure how I would go about verifying it for myself.
So I have sort of a primary question along w/ some followups:
Can I observe an optional property in Swift 4.1?
If so, how can I troubleshoot this, what am I doing wrong?
If not, how can I go about trying to monitor the state of the NSPopUpButton?
Troubleshoots that I've already tried...
added #objc dynamic to the my myPopUpButton declaration
Many properties of many AppKit objects are not KVO-compliant. Unless the documentation specifically says the property is compliant, you should assume it's not compliant. NSPopUpButton's selectedItem property is non-compliant.
The easiest way to be notified that the pop-up button's selected item changed is to set the button's target and action:
override func viewDidLoad() {
super.viewDidLoad()
myPopUpButton.target = self
myPopUpButton.action = #selector(popUpButtonDidFire(_:))
}
#IBAction private func popUpButtonDidFire(_ sender: Any) {
// code to execute goes here
}
Note that if you're creating the pop-up button in a storyboard or xib, you can wire it to the popUpButtonDidFire method by control-dragging from the pop-up button to the view controller.
As mentioned in the comments in macOS Cocoa Bindings and Swift's property observers are a very powerful way to observe values, even in prior Swift versions. An outlet is not needed.
Create a property and use the didSet observer
#objc dynamic var selectedObject : MyObject? {
didSet {
}
}
In Interface Builder in Bindings Inspector bind Selected Object to the target controller Model Key Path > selectedObject.
MyObject is the type of the represented object of the menu item. If nothing is selected selectedObject is nil. You can bind also Selected Index, Selected Tag or Selected Value (but not simultaneously).
I have a UIViewController with a UILabel that needs to display either "lbs" or "kg". My app has a settings screen (another UIViewController) that is presented modally over the first view controller and the user can select either of the two units and save their preference. If the units are changed and the modal settings screen is dismissed, I of course want the label on the first view controller to be updated with the new units value (but without refreshing the whole view). I thought I knew how to make it work, but evidently I don't.
On my modal settings screen, I have a UISegmentedControl to allow the user to select units. Anytime it's changed, this function updates userDefaults:
func saveUnitsSelection() {
if unitsControl.selectedSegmentIndex == 0 {
UserDefaultsManager.sharedInstance.preferredUnits = Units.pounds.rawValue
} else {
UserDefaultsManager.sharedInstance.preferredUnits = Units.kilograms.rawValue
}
}
Then they would likely dismiss the settings screen. So, I added this to viewDidLoad in my first view controller:
override func viewDidLoad() {
super.viewDidLoad()
let preferredUnits = UserDefaultsManager.sharedInstance.preferredUnits
units.text = preferredUnits
}
That didn't work, so I moved it to viewWillAppear() and that didn't work either. I did some research and some caveman debugging and found out that neither of those functions is called after the view has been loaded/presented the first time. It seems that viewWillAppear will be called a second time if I'm working within a hierarchy of UITableViewControllers managed by a UINavigationController, but isn't called when I dismiss my modal UIViewController to reveal the UIViewController underneath it.
Edit 1:
Here's the view hierarchy I'm working with:
I'm kinda stuck at this point and not sure what to try next.
Edit 2:
The user can tap a 'Done' button in the navigation bar and when they do, the dismissSettings() function dismisses the Settings view:
class SettingsViewController: UITableViewController {
let preferredUnits = UserDefaultsManager.sharedInstance.preferredUnits
// some other variables set here
override func viewDidLoad() {
super.viewDidLoad()
self.navigationController?.navigationBar.topItem?.title = "Settings"
navigationItem.rightBarButtonItem = UIBarButtonItem(title: "Done", style: .Plain, target: self, action: #selector(self.dismissSettings(_:)))
if preferredUnits == Units.pounds.rawValue {
unitsControl.selectedSegmentIndex = 0
} else {
unitsControl.selectedSegmentIndex = 1
}
}
func dismissSettings(sender: AnyObject?) {
navigationController?.dismissViewControllerAnimated(true, completion: nil)
}
}
THE REAL PROBLEM
You misspelled viewWillAppear. You called it:
func viewWillAppear()
As far as Cocoa Touch is concerned, this is a random irrelevant function that hooks into nothing. You meant:
override func viewWillAppear(animated: Bool)
The full name of the first function is: "viewWillAppear"
The full name of the second function is: "viewWillAppear:animated"
Once you get used to this, the extreme method "overloading" that Cocoa Touch uses gets easier.
This is very different in other languages where you might at least get a warning.
The other lesson that everyone needs to learn when posting a question is: Include All Related Code!
Useful logging function I use instead of print or NSLog, to help find these things:
class Util {
static func log(message: String, sourceAbsolutePath: String = #file, line: Int = #line, function: String = #function, category: String = "General") {
let threadType = NSThread.currentThread().isMainThread ? "main" : "other"
let baseName = (NSURL(fileURLWithPath: sourceAbsolutePath).lastPathComponent! as NSString).stringByDeletingPathExtension ?? "UNKNOWN_FILE"
print("\(NSDate()) \(threadType) \(baseName) \(function)[\(line)]: \(message)")
}
}
[Remaining previous discussion removed as it was incorrect guesses]
My goal is to safe a reference from the button, label or textfield inside a variable.
The problem is that I don't know on which control the user tapped.
I am having a simple application which looks like this:
The user can touch any control.
It is easy enough with just those three controls because I can drag in a action. But if I am having many of them I can't handle them all over the action methods. Is there a general way in which I can safe a reference to the control in a variable so that I can know which of the controls is the active one?
Edit
As suggested I am using a function and assigning the variable to the sender of the function. This is how it looks in code:
var currentObject: NSTextField!
override func viewDidLoad() {
super.viewDidLoad()
myTextfield.action = #selector(myAction)
}
func myAction(sender: NSTextField)
{
print("aktuell: \(sender)")
currentObject = sender
}
As you can see this only works for a NSTextfield. Is there a way in which the function works for every control?
Set the tag attribute for each item, and then you can check sender.tag to identify which object is calling it.
To set the tag, select the Attributes inspector in Storyboard (upper right side - middle button of Utilities) and look for this section: