In my project I have two view controllers one that lists all the core data stored in a table view and a second that allows the user to input data to be stored. However when I click the back button on the navigation controller on the second it fails to refresh the tableView.
I have tried [self.tableView reloadData] in the viewDidLoad as a bit of a long shot but no joy.
How would i go about refreshing the data when the user clicks back?
Many thanks
Danny
The shortest route would be to move [self.tableView reloadData] from viewDidLoad to viewDidAppear but I would suggest using a delegate or callback so that it only reloads when necessary.
Related
In my app, there are tabs. I have one tableviewcontroller that contains messages and I have implemented pull to refresh so that works fine. However, if the user goes from the message tab to another tab and then back to the message tab, the uitableview doesn't reload and the user has to pull to refresh. I have thought of putting [self.tableview reloadData] or [self loadObjects] (i am using Parse) in viewDidLoad/viewWilAppear, but that doesn't seem to work...it's because they are only called when the view controller is initially visited right? So I'm wondering as to where I should put that code so that the table view can be reloaded every time the view controller is revisited?
viewWillAppear and viewDidAppear are both called every time the view controller appears. If you call reloadData in one of those methods then it will refresh the table view.
I think your problem is you aren't updating your data source. You will need to make another call to Parse otherwise your table view will just reload with the same data.
I don't think that this behavior is desirable. I suggest you tu wait for a reasonable timeout before updating data, or your user will experience lags and high network usage.
However to do that, you should set a delegate that fires when the corresponding view is loaded (take a look here how to get the event that switch tab menu on iphone ) and then call
[yourTableView reloadData]
inside didSelectViewController
In my test project I have a ViewController and a TableViewController controller embedded in a Navigation Controller. The ViewController is the main view, and the user can navigate to the TableViewController and then return back to the ViewController.
I am using a 'push' segue when going from ViewContoller>TableViewController, and the TableViewController is dismissed using [self dismissViewControllerAnimated:YES completion:nil]; when the user wishes to go back to ViewController.
In ViewController, I have a button that changes the text on a label:
-(IBAction)onButtonPress:(id)sender {
_myLabel.text = #"New Label Text";
}
When navigating to TableView, and then back to ViewController, the change in the _myLabel.text has been lost and the original text is restored. What is the best way to ensure UI data is retained when navigating between views? I might only have one label in this project, but at some point I will have many UI elements, for example, WebViews that need to keep a page loaded when the user navigates away and then comes back.
What would you suggest is the best method to implementing this?
Thanks for your time.
First of all, View is your data representation, any data is your Model. So you may store Model with its entities and values. Your controllers manage data to represent it on View or to change Model according to user actions in View.
So add some Model-object for storing _myLabel.text. And use this object for both controllers in your app.
Try to remove setting the text from the ViewWillAppear or ViewDidAppear method, put it in ViewDidLoad.
This is just to as for advice for the best way to do the following;
I have a tableview which is populated by two arrays; when rowatindexpath is selected takes me to another viewcontroller which displays the data. All is working fine: however, I need to move back to the tableview to display the same data (which now has been released). which would be the best procedure to call back the data? do I pass the data back and forth between the tableview everytime or write the data to a plist and call it back on tableview reload.
Thanks for your time!
To pass data down a stack of controllers the usual approach is to use a delegate protocol on the 'detail' VC that is implemented by the 'master' VC.
It's a common question - I've got an example application that demonstrates this https://bitbucket.org/abizern/delegation-example
Which reminds me, I should update it for iOS 7.
It can easily be achieved by reloadData in viewWillAppear: method.
make a NSMutableArray in SingletonClass or in your application's AppDelegate and update/delete values from it from your DetailView
Once you are in your UITableView VC just reloadData in viewWillAppear:
I have an tabbed application that captures data, stores it using NSUserDefaults and presents a readout in a table that is contained in a UIViewController. I am using a navigation controller between the tab view controller and the data view. The data view is then connected to a history view controller which is a child view controller. The history also has a table.
When you press a row in the history view, the app is supposed to transition back to the data view and present the readout for the history. This is done by making the data the first NSUserDefault which is then presented in the data view. THe transition I am using is
[self.navigationController popToRootViewControllerAnimated:YES];
This transitions back to the data view successfully however it does not change the data in the view. However,when I remove that code and press the row and then press back, the readout is changed. How do I make the readout change on press of the row?
Try to use delegates/protocol,
Set your dataview as delegate to the protocol in history view. Before calling pop, call the delegate action. Then in the action, just refresh ur view in dataview and then call poptoroot.
Just google protocol/delegate example, there should be many.
Delegates / Protocols. The answers are abundant here for passing data between view controllers.
passing-data-between-view-controllers
All that I ended up having to do was implement
[self.dataTable reloadData]
I have a simple iPhone app based on a navigation controller. There are two view controllers, VC1 and VC2, both with table views. VC2 also has a custom table cell. When a user selects a row in VC1, VC2 is pushed on to the stack. When the user selects the back button it's removed. Typical navigation stuff.
The problem I have is that the data in the cells in VC2 persists when the back button is pressed, so that when the user selects a different row in VC1, VC2 is pushed back on to the stack with the 'old' data in the cells, before the methods in VC2 reload the data.
I want to make sure that the data in the table in VC is removed every time the back button is pressed. I've tried releasing the tableview using viewWillDisappear, but it's not working. What's the recommended way of dealing with this situation? I've looked at the docs but it's not obvious (to me at least).
Try out this code snippet in viewWillDissapear or dealloc method.
if(yourTableViewCellObject) [yourTableViewCellObject release];
if(yourTableViewCellObject) yourTableViewCellObject=nil;
This might work.
I've used this technique several times since I asked the original question. As I mentioned in my comment to #Aditya, I've found that the easiest way to deal with this is to use viewWillDisappear to hide the tableview with the 'old' data, and when the user navigates back to the page, wait until the 'new' data is loaded into the table before making the tableview visible again.