My app contains TabBar controller with 5 viewcontrollers. It is possible to click on a button in each of viewcontrollers which will popup another view in which user can choose a setting. The button (which was clicked) is supposed to change its background according to chosen setting in each viewcontroller. So if the user clicks on button in VC1 and chooses the setting, this information should spread into all of the other VCs so that the button has the same background.
I am using storyboards, and I know that this is easily possible between 2VCs using segues, protocols, closures... I cannot find a proper way to spread information to more than 2VCs.
The only solution I can think of is usage of UserDefaults. I would save an information about a button setting and then call ViewWillAppear in each VC, where the background of the button would be set according to the value in UserDefaults. Is there a better solution, please?
EDIT:
As #cora mentioned in the comments, I was able to solve this using Notification Center.
You have several options, including:
Pass an array of the tab controllers to your "popup settings" controller and call a "settingSelected" func in each one directly.
Using Protocol / Delegate pattern, you could create an array of delegates in your "popup settings" controller.
You can use Notification Center.
You could subclass the button and use UIAppearance proxy.
Which approach to use will depend on a number of factors, based on exactly what all you need to do (are there other "settings"? or only that button background?)
You may want to search for swift using themes to see various different approaches.
“Is there a better solution, please?”
Not necessarily. Is this in fact a user default, to be preserved between launches? Then this is exactly what user defaults are for.
If not, then at least you need some central location where information about the current button color can be stored. An obvious candidate here is the tab bar controller itself. It gets notified every time there is a tab bar item switch, so it’s a perfect candidate.
Since you have mentioned you are using a UITabbarController, you can use an instance of UITabbarController and then access .viewControllers property of it and call their added public methods to get them triggered on events that you add. Additionally, using Notification Center makes more sense to me since your code will be more readable. Sometimes Notifications can just get a little confusing for new developers who are working on your code.
Related
I have been asked this question many times in the interview searched every where didn't get any proper answer.So finally posting this question here.
You may go through this.
Yes, you can have multiple windows. A key window is the one who receives the user input.
Starting with Rob's answer I played around a bit and would like to write down some notes for others trying to get information on this topic:
It is not a problem at all to add another UIWindow. Just create one
and makeKeyAndVisible. Done.
Remove it by making another window
visible, then release the one you don't need anymore.
The window that is "key" receives all the keyboard input.
UIWindow covers everything, even modals, popovers, etc. Brilliant!
UIWindow is always in portrait implicitly. It does not rotate.
You'll have to add a controller to the new window's root controller and let that handle rotation.
(Just like the main window) The window's level determines
how "high" it gets displayed. Set it to UIWindowLevelStatusBar to have it cover everything.
Set its hidden property to NO. A 2nd
UIWindow can be used to bring views on the screen that float on top of everything. Without creating a dummy controller just to embed that in a UIPopoverController.
It can be especially useful for iPhone where there is no popover controller but where you might want to mimic something like it.
And yes, it solved, of course, my problem: if
the app resigns activation, add a cover window over whatever is
currently shown to prevent iOS from taking a screenshot of your
app's current content.
Generally one application require only 1 UIWindow, but still there may be some scenarios where you need to use multiple UIWindow in one application.
For example, you wish to show a view on the top of system AlertViews, or can the default Keyboard.
UIWindows are the special UIViews, for which their display order is controlled by .windowLevel property.
You don't need to add a new UIWindow as a subview of any of view. You can simply create a new UIWindow and call either window setHidden:NO or window makeKeyAndVisible depend on the level, you have given to it.
There are three default window enum levels defined:
UIWindowLevelNormal
UIWindowLevelStatusBar
UIWindowLevelAlert
Of course it can have multiple windows. Just, only one to be displayed at a time, that's the keyWindow. You can have multiple windows stored in array or whatsoever, and make them keyWindow when you want to display them.
And, yeah, read the documentation #Mannopson suggested, it's very useful.
Sorry, the question isn't really clear, but basically I want a button or a label or something like that that says "notifications" and a small red square (like Facebook) that displays the number of notifications that user has (if they have any). How would I go about doing that? I'm not too advanced with UI design in iOS yet. I'm coming from an Android background so feel free to use any comparisons if there are any.
What you are referring to is called a badge. Some native controls have them (tab bar buttons come to mind), but most do not.
If you are using a tab bar controller, you can set the badge value from the UIViewController. Something like this:
[[self tabBarItem] setBadgeValue:#"1"];
If you are looking to implement a custom one, it could be easily accomplished with a UIView and a UILabel. Add a badge view to what ever view based control you are creating, then add a label to that badge view and set its text. There are probably lots of third party ones floating around the web already though.
I'm using UIReferenceLibraryViewController to pop up a dictionary to define certain words in my application. It's a very bare-bones controller, and I'm calling it into a smaller view on my main view (akin to a sidebar) rather than with a UINavigationController. As a result, the "Done" button that it includes does nothing when I tap it.
Can I either hide, or customize the behaviour of this Done button?
Failing that, or alternatively, could I get the contents of the definition in some format or other (HTML, XML, NSData, etc.), to display in my own way?
I do have a third-party dictionary in my app already but the definitions it gives are kinda hit-and-miss, and I'd prefer to use the Apple ones if at all possible.
From experience of a DMCA takedown notice from the dictionary provider, you cannot manipulate this view controller in any way. If you do, you are violating contracts and open yourself up to legal action.
I have several view controllers each of them has a label or a button. I want to change visible view controller button's or label's text from the AppDelegate. I know that it is a bad practice but I in the AppDelegate runs a background thread which looks fow new images for user on the server and if there are ones it must update new images counter in the label on the navigation bar of the current dispalyed view.My idea was to use in the AppDelegate.m next code: (ControllerWhichLabelIWantToChange*) self.navigationControllerClass.visibleviewcontroller. ... But here I can't see a label or a button for which I define a property in ControllerWhichLabelIWantToChange. So the question how can I access elements of different view controllers from the AppDelegate and change them?
One suggestion, which might be better for you, is to use NSNotificationCenter to send notifications on various changes. Any view wishing to refresh themselves may respond to such notifications. This is a common practice. Say, for example, you are processing theme data in the background, and you've got 20 live views that require theming, you could post a notification when your background process has completed, and all views that are observing the notification will be notified, and they can update themselves.
Currently I am using UIKeyinput but it is only sending a single delteBackward event even when I hold down the delete key for a long time.
How can I make it send me multiple event calls when I hold delete down for a long time?
There is no easy way to have the system keyboard do auto-repeat. These leaves you with two options:
Fake it by using an overlay on the keyboard (see the comment by #pho0)
Implement a custom keyboard, install it as the inputView for your view or view controller and implement a custom protocol that supports auto-repeat.
Solution 1 works well if you only need the delete key to auto-repeat, but if you need all the keys to auto-repeat the overlay code becomes as complex as the custom keyboard option. (The overlay needs a rectangle for each key, so why not just replace the underlaying keyboard).
Solution 2 involves a certain amount of "up-front" work... One way you might do this is define a key cap class (like a physical key) and a keyboard layout class.
I have implemented both solutions in projects I have worked on, but I currently use solution 2 since I can create whatever keyboard I like. In the simple case the use need never know that it is not the system keyboard. For power users they can customize the keyboard as they see fit.
For what it is worth, I found it useful to have the keyboard class be dumb; it just communicates that a key has transitioned to being down or has transitioned to being up. An additional class above that decides what action should be taken.
In some ways, I know this is not the answer you were looking for, but I hope it helps,
IDZ
One thing I've seen people do is put a fake button on top of the keyboard button. When someone is holding down on it, have a timer remove the last letter every time it fires.
Hope this helps.