I am new to ios development and I am trying to use some methods in different view controllers in regular intervals of time (using same methods in different view controllers).
Can anyone please tell me what is the best method for this?
Thanks in advance!
I'd suggest using protocol for this. You can never know when you want different method behaviour for different controllers. And you can always implement default behaviour in private category of generic uiviewcontroller.
Maybe you could try to implement this method in a customViewController that would be subclassed by these viewController and than every viewController would have access to these method.
Alternate way would be to implement it on the appDelegate or on a common tabBarController, navigationController (or whatever) and so every viewController would have access to it.
If the time interval has to be the same for every viewControler, you should do only one time interval and iterate on your viewControllers
Related
My situation is, I have a navigation controller(nv) with root view controller(rootVC). And another view controller(firstChildVC) pushed to rootVC. And one more view controller(secondChildVC) pushed to firstChildVC. (In real case, I have more subsequence child view controllers) After API calls and some calculations in secondChildVC, I need to pass some data from secondChildVC back to rootVC and popToRootViewController to show some data.
I don't think delegate and closures are good choice in this case. The only thing I could come up with is using NotificationCenter. Just what to know is there any better way to do this?
Thank you in advance.
You can try this inside the SecondVC then pop to root
if let root = self.navigationController?.viewControllers.first as? RootVC {
root.sendData(data)
}
I think there are three valid ways to do this without overly tightly coupling things:
Notification Center
Closures
Delegate pattern
The right way is not a simple choice. It really depends on the details. You mention making an API call. Assuming this is all managed in a separate object and not coded into your view controller code, I would have the object making the API call post a notification and the view controllers can each listen and do whatever is appropriate.
There are two other ways to do this, one is using Delegates another one is Closures
I need a couple of my view controllers to know when Persons dictionary is getting changed.
I have created a protocol, but as I understand, the delegate property can have only one delegate, and not an array of delegates.
I know I can implement this using the NSNotification, but is there any way to do it with delegation?
Thanks!
Delegates are meant to be for One to One.
For multiple listeners NSNotification is the way to go, as you know.
Is it possible to communicate with a viewcontroller after a segue switched to another viewcontroller?
I want to know, because I need data from a viewcontroller passed on to the next viewcontroller,
but I just can't figure out how to get data from one viewcontroller to another, as they have no unique names or something which I can use to communicate with.
So can someone tell me:
If it is possible to communicate between viewcontrollers, and if possible, how?
Usually you do it the other way around, pushing values from the source to the destination. If you implement prepareForSegue in the view controller that is going to be segue'd out, you can use
[segue destinationViewController]
to get a reference to the destination view controller.
Then you can set any values in that controller that are needed using properties on that controller before it segues in.
I have searched for tutorials about making a MVC based iPhone app, but without success
Goto ITunesU and look for Paul Hegartys "iPad and iPhone Application DEvelopment" from stanford university
very good!
try the views presentingViewController property.
A typical OOP pattern is to create yet another object, a Model object (MVC paradigm), connect all the view controllers that need to communicate with this Model object, and pass any shared state or variables by setting and getting properties in this Model object. A common shortcut for very small apps is to use the App Delegate as a Model object, as any other controller can get a reference to the app delegate. But this shortcut is not very extensible to larger or reusable code.
I've recently started developing for the iPhone and so far I'm doing pretty good but there's this basic pattern I really don't seem to get.
Say, I have a TabBar with two views and a custom delegate protocol, thus my structure is the following:
AppDelegate.h/.m
myDelegateProtocol.h
FirstViewController.h/.m
SecondViewController.h/.m
MainView.xib
FirstView.xib
SecondView.xib
Now I want to achieve the following: I placed a button in the FirstView.xib and I'd like the IBAction which it invokes (inside FirstViewController ofc.) to send a message to the SecondViewController ([self.delegate tellSecondViewContrToSayHi]) and invoke another method which simply prints a log into the console saying "hi I'm here."
So far I know what I need to do in theory:
Specify the protocol.
Implement the protocol in the SecondViewController.
Create an id< myDelegateProtocol > delegate inside my FirstViewController,...AND last but not least:
Set the self.delegate = secondViewControllerObject.
Now, nr.4 is where the problem's at. How on earth do I link the delegate to the other viewController? I mean I'm not the one instantiating the views as the tabBar kinda does that for me,... any advise? Or am I just way too tired to notice a really stupid thing I did somewhere?
Theoretically the same question also applies to the target:action: thing,... I mean, how do I define the target?
Thanks a lot,
wasabi
You have the right idea, assuming that you want relatively tight coupling between these controllers via that delegate protocol.
Since neither controller knows about the other until that delegate property is set you need to have some object which has a reference to both of them wire up that relationship. In your case that's probably the application delegate which can create both controllers, set one as the delegate of the other, and pass both along to your tab bar controller.
What you might actually want is to have the app delegate give both controllers a reference to some shared model object. Your FirstViewController can update that model when you tap a button and your SecondViewController can observe changes to the model to update it's display (or just update its view when it appears based on the current model state). That way your controllers don't need to know anything about each other.
So essentially I'm inserting "startViewController" into "mainViewController" now of course I can access startViewControllers methods from mainViewController but I was wondering how to do the opposite? Occasionally startViewController will need to call something in mainViewController and I was just wondering how I do this?
Thanks in advance.
Add an ivar of your mainViewController to your startViewController and set this when showing the view.
Or you can design a nice clean protocol, and make one view the delegate of the other.