Hi I have a quiz app that I am working on, and on my RootViewController I have two buttons with action methods, now when I press on one of the buttons I get my questionViewController and text is loaded into specific fields, I do this by using the viewDidLoad method. When I go back to the RootViewController and click on a different button I want to show the same questionViewController but with different text, how can I go about doing this?
I just finished a project with similar requirement. One way to do this is to use static variable and class method in your questionViewController class.
You could implement viewDidAppear: on your questionViewController, and set the text there instead of viewDidLoad.
You could also implement a method on questionViewController, that updated the text fields, and call this method from the RootViewController.
Related
Playing around with some Objective-C (well, iOS) and have done the following... loaded some UIButtons programmatically into a UIScrollView. That works well. Though I've always just connected UIViewControllers together using control-click and drag. Now I've created buttons programmatically, I have no idea how to go from one view controller to another in a Storyboard because there is nothing to drag from!
I'm not really sure what code to post as such, because I haven't done anything that /nearly/ works or doesn't work as such. I get how to do it with XIBs. But I suppose the question is : 3 UIButtons have been created programmatically and I have 3 UIViewControllers. How do I access those ViewControllers using my UIButtons?
Thanks
In the Interface builder view control click and drag from the viewcontroller icon under the first view controller, to the middle of the second view controller. A segue will be created, selected the appropriate type.
Now select the segue and in the inspector give it a unique identifier (say 'myNewSegue').
Now in your first viewcontroller you can create a method that has the following code:
-(void)myButtonAction:(id)sender {
[self performSegueWithIdentifier:#"myNewSegue" sender:self];
}
And add this method as a target action to your button:
[myButton addTarget:self
action:#selector(myButtonAction:)
forControlEvents:UIControlEventTouchUpInside];]
A segue doesn't have to have a button at the leading end of it; you can instead draw it from an entire view controller to another. You can also give a segue an identifier, a string that's used as a name for that segue. Once you've done that, you can programmatically trigger that segue by calling -performSegueWithIdentifier:sender:.
To actually call -performSegueWithIdentifier:sender:, though, you'll need to connect the button to a target and action. If you've never done that, read the Event Handling Guide for iOS in your documentation.
I am trying to use a variable (birthDateLabel) in two view controllers that are separated via a modal but use the same view controller class (CreateAccountViewController). The label works in the view that it is set in but after [self dismissViewControllerAnimated:YES completion:nil]; is run the varriable is reset, how can I retain it?
Order of operations:
The first instance of CreateAccountViewController is run
A button is tapped to go to a new instance of CreateAccountViewController but this instance has a different view with a UIDatePicker to set the birthDateLabel variable.
The birthDateLabel is set
The user taps done and dismissViewControllerAnimated is run
The app updates a UILabel on the first instance of CreateAccountViewController
Step 5 is what does not work, if I put the label on the view as the picker it works but when the modal is dismissed the variable is reset. How can I keep the variable set after the modal is dismissed? Or is my only option to create separate view controller classes?
I tried to do my best explaining this, but if you need me to explain it more just comment.
The standard way to do this is to use a delegate. The fact that your two controllers are both instances of the same class doesn't make any difference, other than they will both have a variable called birthDataLabel. The value of that variable is specific to each instance, just as it would be if these were of two different classes.
So, you should do it the right way, which is to create a delegate protocol in your second instance, and have the first one set itself as the delegate when it first presents the second one.
#rdelmar provides the most technically correct answer, but if it's just one value you could simply use nsuserdefaults. If the number begins to expand creating a delegate might be a smart choice.
My Setup
I have a ViewController, where users type some sort of text in there. Call it InputViewController.
I have a UIView (in a separate class), where I draw a navigation bar that has a gradient (I override drawRect for Core Graphics, hence I need to to have in a separate class) which has a button. The button takes you to a MapViewController, which allows you to add a location tag to your input. Once a location tag is added, I would like to change the button's image.
My Problem
Once the button is tapped, I need to send the user's input to the MapViewController, where a delegate is also implemented and will pass back some information back to the InputViewController. The issue here is that the button resides in the separate UIView. One way to do this is pass the UIView the information once they are set, which in turn would be passed to the MapViewController once the button is tapped. The problem here would be the delegate as the delegate needs to return to the InputViewController and not the `UIView.
I was wondering if its possible to move the UIView into the InputViewController, including the drawRect method for that view. If so, how can I do that? If not, what are other ways/suggestions I can do to have the above set up?
I guess you need to use NSNotifications for sending messages to your classes. See this.
The structure of my MainStoryboard is:
->Tab Bar Controller -> Navigation Controller -> View Controller (Search)
The behaviour I want to have is that when the user re-selects the Search tab, the UIScrollView on it scrolls to the top. I am unsure how to get the event from the TabBarController, however.
I've been looking at a lot of stuff about UITabBarDelegate, particularly:
- (void)tabBar:(UITabBar *)tabBar didSelectItem:(UITabBarItem *)item
I have, not quite managed to get this to work properly though. I am very unsure about how to go about setting the delegate (assuming that is the way it's done). I've tried hooking it up in IB, but it wouldn't let me. I also tried to get the UITabBar from the AppDelegate (after looking at some seemingly-related answers).
Any pointers will be greatly appreciated (unless they're null).
UITabBar *aTabBar = [UITabBarItem alloc] init];
....Any other modifications you want to make to aTabBar....
[aTabBar setDelegate:self]
Don't forget to add "<UITabBarDelegate>" to the "#interface" part of whatever object you're trying to designate as the delegate.
For my own code, I usually use some object that isn't the application delegate (as the app delegate is usually meant for application level events like "application is suspending" or "application is coming back into foreground"). If you add "<UITabBarDelegate>" to your Search view controller, make sure that whatever you do with the "didSelectItem" method is applicable only to the Search view controller. Otherwise instantiate some different object if you want to do actions on various view controllers based on which tab bar item is being displayed.
I made a viewController class which has a button, an input and a label.
What I want to implement is that when user click the button, a new view will be pushed and the input text will be showed in the label.
I used UINavigationController to memorize the text in input and set the logic in 'pushNext', which is the IBAction of the button, and the viewWillAppear method is used to put the text stored in UINavigationController into label.
I used NSLog to track the proc, and found that viewWillAppear always be called earlier than pushNext? But when I run the example code in my book, the called order was oppsite!
Why? Is there any attention to use these two methods?
The order should be
viewDidLoad
viewWillAppear
viewDidAppear